CVE-2025-26466

EUVD-2025-5920

28.02.2025, 22:15

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.

Provider	Type	Base Score	Atk. Vector	Atk. Complexity	Priv. Required	Vector
NIST	Primary	5.9 MEDIUM	NETWORK	HIGH	NONE	CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H

Base Score

CVSS 3.x

EPSS Score

Percentile: Unknown

Affected Products (NVD)

Vendor	Product	Version
openbsd	openssh	9.5:p1
openbsd	openssh	9.6
openbsd	openssh	9.6:p1
openbsd	openssh	9.7
openbsd	openssh	9.7:p1
openbsd	openssh	9.8
openbsd	openssh	9.8:p1
openbsd	openssh	9.9
openbsd	openssh	9.9:p1
canonical	ubuntu_linux	24.04
canonical	ubuntu_linux	24.10
debian	debian_linux	11.0
debian	debian_linux	12.0
debian	debian_linux	13.0

𝑥

= Vulnerable software versions

Debian Releases

Debian Product

Codename

openssh

bookworm	1:9.2p1-2+deb12u7 fixed
bookworm (security)	1:9.2p1-2+deb12u9 fixed
bullseye	1:8.4p1-5+deb11u3 fixed
bullseye (security)	1:8.4p1-5+deb11u6 fixed
forky	1:10.2p1-6 fixed
sid	1:10.3p1-1 fixed
trixie	1:10.0p1-7+deb13u1 fixed
trixie (security)	1:10.0p1-7+deb13u2 fixed

Common Weakness Enumeration

CWE-770 - Allocation of Resources Without Limits or Throttling
The software allocates a reusable resource or group of resources on behalf of an actor without imposing any restrictions on the size or number of resources that can be allocated, in violation of the intended security policy for that actor.

References

https://access.redhat.com/security/cve/CVE-2025-26466

https://bugzilla.redhat.com/show_bug.cgi?id=2345043

https://seclists.org/oss-sec/2025/q1/144

https://www.qualys.com/2025/02/18/openssh-mitm-dos.txt

http://seclists.org/fulldisclosure/2025/Feb/18

http://seclists.org/fulldisclosure/2025/May/7

http://seclists.org/fulldisclosure/2025/May/8

https://bugzilla.suse.com/show_bug.cgi?id=1237041

https://security-tracker.debian.org/tracker/CVE-2025-26466

https://security.netapp.com/advisory/ntap-20250228-0002/

https://ubuntu.com/security/CVE-2025-26466

https://www.openwall.com/lists/oss-security/2025/02/18/1

https://www.openwall.com/lists/oss-security/2025/02/18/4

https://www.vicarius.io/vsociety/posts/cve-2025-26466-detection-script-memory-consumption-vulnerability-in-openssh

https://www.vicarius.io/vsociety/posts/cve-2025-26466-mitigation-script-memory-consumption-vulnerability-in-openssh

https://www.qualys.com/2025/02/18/openssh-mitm-dos.txt