CVE-2021-41991

Publication date 18 October 2021

Last updated 18 August 2025

Ubuntu priority

Medium

Why this priority?

Cvss 3 Severity Score

7.5 · High

Score breakdown

Description

The in-memory certificate cache in strongSwan before 5.9.4 has a remote integer overflow upon receiving many requests with different certificates to fill the cache and later trigger the replacement of cache entries. The code attempts to select a less-often-used cache entry by means of a random number generator, but this is not done correctly. Remote code execution might be a slight possibility.

Read the notes from the security team

Status

Package Ubuntu Release Status
strongswan 25.10 questing
Fixed 5.9.1-1ubuntu3.1
25.04 plucky
Fixed 5.9.1-1ubuntu3.1
24.10 oracular
Fixed 5.9.1-1ubuntu3.1
24.04 LTS noble
Fixed 5.9.1-1ubuntu3.1
23.10 mantic
Fixed 5.9.1-1ubuntu3.1
23.04 lunar
Fixed 5.9.1-1ubuntu3.1
22.10 kinetic
Fixed 5.9.1-1ubuntu3.1
22.04 LTS jammy
Fixed 5.9.1-1ubuntu3.1
21.10 impish
Fixed 5.9.1-1ubuntu3.1
21.04 hirsute
Fixed 5.9.1-1ubuntu1.2
20.04 LTS focal
Fixed 5.8.2-1ubuntu3.3
18.04 LTS bionic
Fixed 5.6.2-1ubuntu2.7
16.04 LTS xenial
Fixed 5.3.5-1ubuntu3.8+esm1
14.04 LTS trusty
Fixed 5.1.2-0ubuntu2.11+esm1

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Notes

mdeslaur

affects 4.2.10+

Severity score breakdown

Parameter Value
Base score 7.5 · High
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-5111-1
    • strongSwan vulnerabilities
    • 19 October 2021
    • USN-5111-2
    • strongSwan vulnerability
    • 19 October 2021

Other references