CVE-2018-20843
Publication date 24 June 2019
Last updated 11 July 2025
Ubuntu priority
Cvss 3 Severity Score
Description
In libexpat in Expat before 2.2.7, XML input including XML names that contain a large number of colons could make the XML parser consume a high amount of RAM and CPU resources while processing (enough to be usable for denial-of-service attacks).
Status
| Package | Ubuntu Release | Status | 
|---|---|---|
| apache2 | 25.10 questing | 
                                Not affected 
                                
                               | 
| 25.04 plucky | 
                                Not affected 
                                
                               | |
| 24.04 LTS noble | 
                                Not affected 
                                
                               | |
| 22.04 LTS jammy | 
                                Not affected 
                                
                               | |
| 20.04 LTS focal | 
                                Not affected 
                                
                               | |
| 18.04 LTS bionic | 
                                Not affected 
                                
                               | |
| 16.04 LTS xenial | 
                                Not affected 
                                
                               | |
| 14.04 LTS trusty | 
                                Not affected 
                                
                               | |
| ghostscript | 25.10 questing | 
                                Not affected 
                                
                               | 
| 25.04 plucky | 
                                Not affected 
                                
                               | |
| 24.04 LTS noble | 
                                Not affected 
                                
                               | |
| 22.04 LTS jammy | 
                                Not affected 
                                
                               | |
| 20.04 LTS focal | 
                                Not affected 
                                
                               | |
| 18.04 LTS bionic | 
                                Not affected 
                                
                               | |
| 16.04 LTS xenial | 
                                Not affected 
                                
                               | |
| 14.04 LTS trusty | Not in release | |
| libparagui1.1 | 25.10 questing | Not in release | 
| 25.04 plucky | Not in release | |
| 24.04 LTS noble | Not in release | |
| 22.04 LTS jammy | Not in release | |
| 20.04 LTS focal | Not in release | |
| 18.04 LTS bionic | Not in release | |
| 16.04 LTS xenial | Not in release | |
| 14.04 LTS trusty | Not in release | |
| poco | 25.10 questing | 
                                Not affected 
                                
                               | 
| 25.04 plucky | 
                                Not affected 
                                
                               | |
| 24.04 LTS noble | 
                                Not affected 
                                
                               | |
| 22.04 LTS jammy | 
                                Not affected 
                                
                               | |
| 20.04 LTS focal | 
                                Not affected 
                                
                               | |
| 18.04 LTS bionic | 
                                Not affected 
                                
                               | |
| 16.04 LTS xenial | 
                                Not affected 
                                
                               | |
| 14.04 LTS trusty | 
                                Not affected 
                                
                               | |
| sitecopy | 25.10 questing | 
                                Needs evaluation 
                                
                               | 
| 25.04 plucky | 
                                Needs evaluation 
                                
                               | |
| 24.04 LTS noble | Not in release | |
| 22.04 LTS jammy | 
                                Not affected 
                                
                               | |
| 20.04 LTS focal | 
                                Not affected 
                                
                               | |
| 18.04 LTS bionic | 
                                Not affected 
                                
                               | |
| 16.04 LTS xenial | 
                                Not affected 
                                
                               | |
| 14.04 LTS trusty | Not in release | |
| audacity | 25.10 questing | 
                                Not affected 
                                
                               | 
| 25.04 plucky | 
                                Not affected 
                                
                               | |
| 24.04 LTS noble | 
                                Not affected 
                                
                               | |
| 22.04 LTS jammy | 
                                Not affected 
                                
                               | |
| 20.04 LTS focal | 
                                Not affected 
                                
                               | |
| 18.04 LTS bionic | 
                                Not affected 
                                
                               | |
| 16.04 LTS xenial | 
                                Not affected 
                                
                               | |
| 14.04 LTS trusty | Not in release | |
| ayttm | 25.10 questing | Not in release | 
| 25.04 plucky | Not in release | |
| 24.04 LTS noble | Not in release | |
| 22.04 LTS jammy | Not in release | |
| 20.04 LTS focal | Not in release | |
| 18.04 LTS bionic | Not in release | |
| 16.04 LTS xenial | 
                                Needs evaluation 
                                
                               | |
| 14.04 LTS trusty | Not in release | |
| cableswig | 25.10 questing | Not in release | 
| 25.04 plucky | Not in release | |
| 24.04 LTS noble | Not in release | |
| 22.04 LTS jammy | Not in release | |
| 20.04 LTS focal | Not in release | |
| 18.04 LTS bionic | Not in release | |
| 16.04 LTS xenial | 
                                Needs evaluation 
                                
                               | |
| 14.04 LTS trusty | Not in release | |
| coin3 | 25.10 questing | 
                                Not affected 
                                
                               | 
| 25.04 plucky | 
                                Not affected 
                                
                               | |
| 24.04 LTS noble | 
                                Not affected 
                                
                               | |
| 22.04 LTS jammy | 
                                Not affected 
                                
                               | |
| 20.04 LTS focal | 
                                Not affected 
                                
                               | |
| 18.04 LTS bionic | 
                                Vulnerable 
                                
                               | |
| 16.04 LTS xenial | 
                                Vulnerable 
                                
                               | |
| 14.04 LTS trusty | 
                                Vulnerable 
                                
                               | |
| firefox | 25.10 questing | 
                                Not affected 
                                
                               | 
| 25.04 plucky | 
                                Not affected 
                                
                               | |
| 24.04 LTS noble | 
                                Not affected 
                                
                               | |
| 22.04 LTS jammy | 
                                Not affected 
                                
                               | |
| 20.04 LTS focal | Not in release | |
| 18.04 LTS bionic | 
                                Not affected 
                                
                               | |
| 16.04 LTS xenial | 
                                Not affected 
                                
                               | |
| 14.04 LTS trusty | Not in release | |
| matanza | 25.10 questing | Ignored | 
| 25.04 plucky | Ignored | |
| 24.04 LTS noble | Ignored | |
| 22.04 LTS jammy | Ignored | |
| 20.04 LTS focal | Ignored | |
| 18.04 LTS bionic | Ignored | |
| 16.04 LTS xenial | Ignored | |
| 14.04 LTS trusty | Not in release | |
| smart | 25.10 questing | Not in release | 
| 25.04 plucky | Not in release | |
| 24.04 LTS noble | Not in release | |
| 22.04 LTS jammy | Not in release | |
| 20.04 LTS focal | Not in release | |
| 18.04 LTS bionic | 
                                Not affected 
                                
                               | |
| 16.04 LTS xenial | 
                                Not affected 
                                
                               | |
| 14.04 LTS trusty | Not in release | |
| tdom | 25.10 questing | 
                                Not affected 
                                
                               | 
| 25.04 plucky | 
                                Not affected 
                                
                               | |
| 24.04 LTS noble | 
                                Not affected 
                                
                               | |
| 22.04 LTS jammy | 
                                Not affected 
                                
                               | |
| 20.04 LTS focal | 
                                Not affected 
                                
                               | |
| 18.04 LTS bionic | 
                                Not affected 
                                
                               | |
| 16.04 LTS xenial | 
                                Not affected 
                                
                               | |
| 14.04 LTS trusty | Not in release | |
| thunderbird | 25.10 questing | 
                                Not affected 
                                
                               | 
| 25.04 plucky | 
                                Not affected 
                                
                               | |
| 24.04 LTS noble | 
                                Not affected 
                                
                               | |
| 22.04 LTS jammy | 
                                Not affected 
                                
                               | |
| 20.04 LTS focal | Not in release | |
| 18.04 LTS bionic | 
                                Not affected 
                                
                               | |
| 16.04 LTS xenial | 
                                Not affected 
                                
                               | |
| 14.04 LTS trusty | Not in release | |
| vtk | 25.10 questing | Not in release | 
| 25.04 plucky | Not in release | |
| 24.04 LTS noble | Not in release | |
| 22.04 LTS jammy | Not in release | |
| 20.04 LTS focal | Not in release | |
| 18.04 LTS bionic | Not in release | |
| 16.04 LTS xenial | 
                                Fixed 5.10.1+dfsg-2.1ubuntu0.1~esm1 
                                
                                   | |
| 14.04 LTS trusty | 
                                Fixed 5.8.0-14.1ubuntu3+esm1 
                                
                                   | |
| swish-e | 25.10 questing | 
                                Needs evaluation 
                                
                               | 
| 25.04 plucky | 
                                Needs evaluation 
                                
                               | |
| 24.04 LTS noble | 
                                Needs evaluation 
                                
                               | |
| 22.04 LTS jammy | 
                                Needs evaluation 
                                
                               | |
| 20.04 LTS focal | 
                                Needs evaluation 
                                
                               | |
| 18.04 LTS bionic | 
                                Needs evaluation 
                                
                               | |
| 16.04 LTS xenial | 
                                Needs evaluation 
                                
                               | |
| 14.04 LTS trusty | Not in release | |
| wxwidgets2.8 | 25.10 questing | Not in release | 
| 25.04 plucky | Not in release | |
| 24.04 LTS noble | Not in release | |
| 22.04 LTS jammy | Not in release | |
| 20.04 LTS focal | Not in release | |
| 18.04 LTS bionic | Not in release | |
| 16.04 LTS xenial | Not in release | |
| 14.04 LTS trusty | Not in release | |
| cadaver | 25.10 questing | 
                                Needs evaluation 
                                
                               | 
| 25.04 plucky | 
                                Needs evaluation 
                                
                               | |
| 24.04 LTS noble | 
                                Needs evaluation 
                                
                               | |
| 22.04 LTS jammy | 
                                Needs evaluation 
                                
                               | |
| 20.04 LTS focal | 
                                Needs evaluation 
                                
                               | |
| 18.04 LTS bionic | 
                                Needs evaluation 
                                
                               | |
| 16.04 LTS xenial | 
                                Needs evaluation 
                                
                               | |
| 14.04 LTS trusty | Not in release | |
| xmlrpc-c | 25.10 questing | 
                                Needs evaluation 
                                
                               | 
| 25.04 plucky | 
                                Needs evaluation 
                                
                               | |
| 24.04 LTS noble | 
                                Needs evaluation 
                                
                               | |
| 22.04 LTS jammy | 
                                Needs evaluation 
                                
                               | |
| 20.04 LTS focal | 
                                Needs evaluation 
                                
                               | |
| 18.04 LTS bionic | 
                                Needs evaluation 
                                
                               | |
| 16.04 LTS xenial | 
                                Needs evaluation 
                                
                               | |
| 14.04 LTS trusty | 
                                Needs evaluation 
                                
                               | |
| libxmltok | 25.10 questing | Not in release | 
| 25.04 plucky | 
                                Vulnerable 
                                
                               | |
| 24.04 LTS noble | 
                                Fixed 1.2-4.1ubuntu2.24.0.4.1+esm2 
                                
                                   | |
| 22.04 LTS jammy | 
                                Fixed 1.2-4ubuntu0.22.04.1~esm4 
                                
                                   | |
| 20.04 LTS focal | 
                                Fixed 1.2-4ubuntu0.20.04.1~esm4 
                                
                                   | |
| 18.04 LTS bionic | 
                                Fixed 1.2-4ubuntu0.18.04.1~esm4 
                                
                                   | |
| 16.04 LTS xenial | 
                                Fixed 1.2-3ubuntu0.16.04.1~esm2 
                                
                                   | |
| 14.04 LTS trusty | Ignored end of standard support | |
| apr-util | 25.10 questing | 
                                Not affected 
                                
                               | 
| 25.04 plucky | 
                                Not affected 
                                
                               | |
| 24.04 LTS noble | 
                                Not affected 
                                
                               | |
| 22.04 LTS jammy | 
                                Not affected 
                                
                               | |
| 20.04 LTS focal | 
                                Not affected 
                                
                               | |
| 18.04 LTS bionic | 
                                Not affected 
                                
                               | |
| 16.04 LTS xenial | 
                                Not affected 
                                
                               | |
| 14.04 LTS trusty | 
                                Not affected 
                                
                               | |
| cmake | 25.10 questing | 
                                Not affected 
                                
                               | 
| 25.04 plucky | 
                                Not affected 
                                
                               | |
| 24.04 LTS noble | 
                                Not affected 
                                
                               | |
| 22.04 LTS jammy | 
                                Not affected 
                                
                               | |
| 20.04 LTS focal | 
                                Not affected 
                                
                               | |
| 18.04 LTS bionic | 
                                Not affected 
                                
                               | |
| 16.04 LTS xenial | 
                                Not affected 
                                
                               | |
| 14.04 LTS trusty | Not in release | |
| expat | 25.10 questing | 
                                Fixed 2.2.6-2 
                                
                               | 
| 25.04 plucky | 
                                Fixed 2.2.6-2 
                                
                               | |
| 24.04 LTS noble | 
                                Fixed 2.2.6-2 
                                
                               | |
| 22.04 LTS jammy | 
                                Fixed 2.2.6-2 
                                
                               | |
| 20.04 LTS focal | 
                                Fixed 2.2.6-2 
                                
                               | |
| 18.04 LTS bionic | 
                                Fixed 2.2.5-3ubuntu0.1 
                                
                               | |
| 16.04 LTS xenial | 
                                Fixed 2.1.0-7ubuntu0.16.04.4 
                                
                               | |
| 14.04 LTS trusty | 
                                Fixed 2.1.0-4ubuntu1.4+esm1 
                                
                                   | |
| gdcm | 25.10 questing | 
                                Not affected 
                                
                               | 
| 25.04 plucky | 
                                Not affected 
                                
                               | |
| 24.04 LTS noble | 
                                Not affected 
                                
                               | |
| 22.04 LTS jammy | 
                                Not affected 
                                
                               | |
| 20.04 LTS focal | 
                                Not affected 
                                
                               | |
| 18.04 LTS bionic | 
                                Not affected 
                                
                               | |
| 16.04 LTS xenial | 
                                Not affected 
                                
                               | |
| 14.04 LTS trusty | 
                                Not affected 
                                
                               | |
| insighttoolkit | 25.10 questing | Not in release | 
| 25.04 plucky | Not in release | |
| 24.04 LTS noble | Not in release | |
| 22.04 LTS jammy | Not in release | |
| 20.04 LTS focal | Not in release | |
| 18.04 LTS bionic | Not in release | |
| 16.04 LTS xenial | 
                                Needs evaluation 
                                
                               | |
| 14.04 LTS trusty | Not in release | |
| insighttoolkit4 | 25.10 questing | Not in release | 
| 25.04 plucky | Not in release | |
| 24.04 LTS noble | Not in release | |
| 22.04 LTS jammy | 
                                Not affected 
                                
                               | |
| 20.04 LTS focal | 
                                Not affected 
                                
                               | |
| 18.04 LTS bionic | 
                                Not affected 
                                
                               | |
| 16.04 LTS xenial | 
                                Vulnerable 
                                
                               | |
| 14.04 LTS trusty | Not in release | |
| kompozer | 25.10 questing | Not in release | 
| 25.04 plucky | Not in release | |
| 24.04 LTS noble | Not in release | |
| 22.04 LTS jammy | Not in release | |
| 20.04 LTS focal | Not in release | |
| 18.04 LTS bionic | Not in release | |
| 16.04 LTS xenial | Not in release | |
| 14.04 LTS trusty | Not in release | |
| simgear | 25.10 questing | 
                                Not affected 
                                
                               | 
| 25.04 plucky | 
                                Not affected 
                                
                               | |
| 24.04 LTS noble | 
                                Not affected 
                                
                               | |
| 22.04 LTS jammy | 
                                Not affected 
                                
                               | |
| 20.04 LTS focal | 
                                Not affected 
                                
                               | |
| 18.04 LTS bionic | 
                                Not affected 
                                
                               | |
| 16.04 LTS xenial | 
                                Not affected 
                                
                               | |
| 14.04 LTS trusty | Not in release | |
| texlive-bin | 25.10 questing | 
                                Not affected 
                                
                               | 
| 25.04 plucky | 
                                Not affected 
                                
                               | |
| 24.04 LTS noble | 
                                Not affected 
                                
                               | |
| 22.04 LTS jammy | 
                                Not affected 
                                
                               | |
| 20.04 LTS focal | 
                                Not affected 
                                
                               | |
| 18.04 LTS bionic | 
                                Not affected 
                                
                               | |
| 16.04 LTS xenial | 
                                Not affected 
                                
                               | |
| 14.04 LTS trusty | Not in release | |
| vnc4 | 25.10 questing | Not in release | 
| 25.04 plucky | Not in release | |
| 24.04 LTS noble | Not in release | |
| 22.04 LTS jammy | Not in release | |
| 20.04 LTS focal | Not in release | |
| 18.04 LTS bionic | 
                                Vulnerable 
                                
                               | |
| 16.04 LTS xenial | 
                                Vulnerable 
                                
                               | |
| 14.04 LTS trusty | 
                                Vulnerable 
                                
                               | |
| wbxml2 | 25.10 questing | 
                                Not affected 
                                
                               | 
| 25.04 plucky | 
                                Not affected 
                                
                               | |
| 24.04 LTS noble | 
                                Not affected 
                                
                               | |
| 22.04 LTS jammy | 
                                Not affected 
                                
                               | |
| 20.04 LTS focal | 
                                Not affected 
                                
                               | |
| 18.04 LTS bionic | 
                                Not affected 
                                
                               | |
| 16.04 LTS xenial | 
                                Not affected 
                                
                               | |
| 14.04 LTS trusty | Not in release | |
| wxwidgets2.6 | 25.10 questing | Not in release | 
| 25.04 plucky | Not in release | |
| 24.04 LTS noble | Not in release | |
| 22.04 LTS jammy | Not in release | |
| 20.04 LTS focal | Not in release | |
| 18.04 LTS bionic | Not in release | |
| 16.04 LTS xenial | Not in release | |
| 14.04 LTS trusty | Not in release | 
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Severity score breakdown
| Parameter | Value | 
|---|---|
| Base score |  | 
| Attack vector | Network | 
| Attack complexity | Low | 
| Privileges required | None | 
| User interaction | None | 
| Scope | Unchanged | 
| Confidentiality | None | 
| Integrity impact | None | 
| Availability impact | High | 
| Vector | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H | 
References
Related Ubuntu Security Notices (USN)
- USN-4040-1
- Expat vulnerability
- 26 June 2019
- USN-4040-2
- Expat vulnerability
- 26 June 2019
- USN-4852-1
- VTK vulnerabilities
- 15 March 2021
- USN-5455-1
- xmltok library vulnerabilities
- 19 July 2022
- USN-7199-1
- xmltok library vulnerabilities
- 13 January 2025
Other references
- https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=5226
- https://github.com/libexpat/libexpat/pull/262
- https://github.com/libexpat/libexpat/blob/R_2_2_7/expat/Changes
- https://github.com/libexpat/libexpat/pull/262/commits/11f8838bf99ea0a6f0b76f9760c43704d00c4ff6
- https://www.cve.org/CVERecord?id=CVE-2018-20843