CVE-2025-26466
mediumA flaw was found in the OpenSSH package.
Vendor / product: Openbsd — openssh
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.
CVSS
5.9
5.9 (CVSS v3.1)
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H Severity source: NVD CVSS v3.1 (nvd@nist.gov)
Timeline (UTC)
Published: 2025-02-28 22:15
Modified: 2026-11-05 16:17
NVD status: Modified
Last synced 6 days ago
Verified against the source API 2026-11-05 16:48 UTC
Exploitation
Not listed in CISA KEV (as of last catalog sync)
Absence from KEV does not mean a CVE is not exploited. Exploitation status: unknown (no authoritative evidence in our sources).
Affected products
openbsd / openssh 9.5, 9.6, 9.7, 9.8, 9.9
canonical / ubuntu_linux 24.04, 24.10
debian / debian_linux 11.0, 12.0, 13.0
Weakness classification (CWE)
Source: NVD / CISA. “NVD-CWE-Other” and “NVD-CWE-noinfo” mean NVD could not assign a specific weakness.
Mitigation & advisories
No vendor advisory or patch reference tagged by NVD. Check the references below.
References
- https://access.redhat.com/errata/RHBA-2025:6305 secalert@redhat.com
- https://access.redhat.com/errata/RHSA-2025:6993 secalert@redhat.com
- https://access.redhat.com/security/cve/CVE-2025-26466 secalert@redhat.com
- https://bugzilla.redhat.com/show_bug.cgi?id=2345043 secalert@redhat.com
- https://seclists.org/oss-sec/2025/q1/144 secalert@redhat.com
- https://www.qualys.com/2025/02/18/openssh-mitm-dos.txt secalert@redhat.com
- http://seclists.org/fulldisclosure/2025/Feb/18 af854a3a-2127-422b-91ae-364da2661108
- http://seclists.org/fulldisclosure/2025/May/7 af854a3a-2127-422b-91ae-364da2661108
- http://seclists.org/fulldisclosure/2025/May/8 af854a3a-2127-422b-91ae-364da2661108
- https://bugzilla.suse.com/show_bug.cgi?id=1237041 af854a3a-2127-422b-91ae-364da2661108
- https://security-tracker.debian.org/tracker/CVE-2025-26466 af854a3a-2127-422b-91ae-364da2661108
- https://security.netapp.com/advisory/ntap-20250228-0002/ af854a3a-2127-422b-91ae-364da2661108
- https://ubuntu.com/security/CVE-2025-26466 af854a3a-2127-422b-91ae-364da2661108
- https://www.openwall.com/lists/oss-security/2025/02/18/1 af854a3a-2127-422b-91ae-364da2661108
- https://www.openwall.com/lists/oss-security/2025/02/18/4 af854a3a-2127-422b-91ae-364da2661108
- https://www.vicarius.io/vsociety/posts/cve-2025-26466-detection-script-memory-consumption-... af854a3a-2127-422b-91ae-364da2661108
- https://www.vicarius.io/vsociety/posts/cve-2025-26466-mitigation-script-memory-consumption... af854a3a-2127-422b-91ae-364da2661108
- https://cert-portal.siemens.com/productcert/html/ssa-398330.html 0b142b55-0307-4c5a-b3c9-f314f3fb7c5e
- https://www.qualys.com/2025/02/18/openssh-mitm-dos.txt 134c704f-9b21-4f2e-91b3-4a467353bcc0
Data sources
NVD CVE API 2.0 — fetched 2026-11-05 16:48 UTC · record ↗