CVE-2025-5994
Publication date 17 July 2025
Last updated 22 July 2025
Ubuntu priority
A multi-vendor cache poisoning vulnerability named 'Rebirthday Attack' has been discovered in caching resolvers that support EDNS Client Subnet (ECS). Unbound is also vulnerable when compiled with ECS support, i.e., '--enable-subnet', AND configured to send ECS information along with queries to upstream name servers, i.e., at least one of the 'send-client-subnet', 'client-subnet-zone' or 'client-subnet-always-forward' options is used. Resolvers supporting ECS need to segregate outgoing queries to accommodate for different outgoing ECS information. This re-opens up resolvers to a birthday paradox attack (Rebirthday Attack) that tries to match the DNS transaction ID in order to cache non-ECS poisonous replies.
Status
| Package | Ubuntu Release | Status |
|---|---|---|
| unbound | 25.04 plucky |
Fixed 1.22.0-1ubuntu1.1
|
| 24.04 LTS noble |
Fixed 1.19.2-1ubuntu3.5
|
|
| 22.04 LTS jammy |
Fixed 1.13.1-1ubuntu5.11
|
|
| 20.04 LTS focal |
Needs evaluation
|
|
| 18.04 LTS bionic |
Needs evaluation
|
|
| 16.04 LTS xenial |
Needs evaluation
|
|
| 14.04 LTS trusty |
Needs evaluation
|
References
Related Ubuntu Security Notices (USN)
- USN-7666-1
- Unbound vulnerabilities
- 22 July 2025