| Name | CVE-2025-5994 |
| Description | 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. |
| Source | CVE (at NVD; CERT, LWN, oss-sec, fulldisc, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, GitHub advisories/code/issues, web search, more) |
| Debian Bugs | 1109427 |
The table below lists information on source packages.
| Source Package | Release | Version | Status |
|---|---|---|---|
| unbound (PTS) | bullseye | 1.13.1-1+deb11u2 | vulnerable |
| bullseye (security) | 1.13.1-1+deb11u4 | vulnerable | |
| bookworm, bookworm (security) | 1.17.1-2+deb12u2 | vulnerable | |
| sid, trixie | 1.22.0-2 | fixed |
The information below is based on the following data on fixed versions.
| Package | Type | Release | Fixed Version | Urgency | Origin | Debian Bugs |
|---|---|---|---|---|---|---|
| unbound | source | (unstable) | 1.22.0-2 | 1109427 |
https://nlnetlabs.nl/downloads/unbound/CVE-2025-5994.txt
Fixed by: https://github.com/NLnetLabs/unbound/commit/5bf82f246481098a6473f296b21fc1229d276c0f (release-1.23.1)