What’s Vulnerable › Vulnerabilities
CVE-2025-26466: Openssh: denial-of-service in openssh
- Severity: medium (CVSS 5.9 v3.1)
- Exploited in the wild: not listed in CISA KEV
- EPSS: 38.7% probability of exploitation in the next 30 days
- Public exploit or detection template: none known
- Published: 2025-02-28 · updated 2026-10-21
- Weakness: CWE-770
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.
Affected products
- Canonical Ubuntu Linux: 24.04, 24.10
- Debian Linux: 11.0, 12.0, 13.0
- OpenSSH: 9.5-p1, 9.6, 9.6-p1, 9.7, 9.7-p1, 9.8 (+3)
References
- https://access.redhat.com/errata/RHBA-2025:6305
- https://access.redhat.com/errata/RHSA-2025:6993
- 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/
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