| Name | CVE-2025-26466 |
| Description | A flaw was found in the OpenSSH package. For each ping packet the SSH server receives, a pong packet is allocated in a memory buffer and stored in a queue of packages. It is only freed when the server/client key exchange has finished. A malicious client may keep sending such packages, leading to an uncontrolled increase in memory consumption on the server side. Consequently, the server may become unavailable, resulting in a denial of service attack. |
| Source | CVE (at NVD; CERT, LWN, oss-sec, fulldisc, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, GitHub advisories/code/issues, web search, more) |
The table below lists information on source packages.
| Source Package | Release | Version | Status |
|---|---|---|---|
| openssh (PTS) | bullseye | 1:8.4p1-5+deb11u3 | fixed |
| bullseye (security) | 1:8.4p1-5+deb11u4 | fixed | |
| bookworm, bookworm (security) | 1:9.2p1-2+deb12u5 | fixed | |
| sid, trixie | 1:9.9p2-2 | fixed |
The information below is based on the following data on fixed versions.
| Package | Type | Release | Fixed Version | Urgency | Origin | Debian Bugs |
|---|---|---|---|---|---|---|
| openssh | source | bullseye | (not affected) | |||
| openssh | source | bookworm | (not affected) | |||
| openssh | source | (unstable) | 1:9.9p2-1 |
[bookworm] - openssh <not-affected> (Vulnerable code introduced later)
[bullseye] - openssh <not-affected> (Vulnerable code introduced later)
https://www.openssh.com/releasenotes.html#9.9p2
https://www.qualys.com/2025/02/18/openssh-mitm-dos.txt
Introduced with: https://github.com/openssh/openssh-portable/commit/dce6d80d2ed3cad2c516082682d5f6ca877ef714 (V_9_5_P1)
Fixed by: https://github.com/openssh/openssh-portable/commit/6ce00f0c2ecbb9f75023dbe627ee6460bcec78c2 (V_9_9_P1)