CVE-2025-26466
A malicious client may keep sending such packages, leading to an uncontrolled increase in memory consumption on the server side.
Does this matter?
EPSS puts the probability of exploitation in the next 30 days at 38.7%, higher than 99% of all known CVEs. Patch or mitigate before the next change window.
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.
- CVSS 3.1
- 5.9 MEDIUMCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
- EPSS
- 38.68% probability · 99th percentile
- Public exploits
- None in Exploit-DB
- CISA KEV
- Not listed
- Weakness
- CWE-770
- Affected
- openbsd/openssh · canonical/ubuntu linux · debian/debian linux
- Source
- secalert@redhat.com
EPSS moved from 38.7% on 25 October 2026 to 38.7% on 2 November 2026. The dashed line is the ten per cent mark our analysts treat as “patch before the next change window”.
References
- https://access.redhat.com/errata/RHBA-2025:6305
- https://access.redhat.com/errata/RHSA-2025:6993
- https://access.redhat.com/security/cve/CVE-2025-26466Third Party Advisory
- https://bugzilla.redhat.com/show_bug.cgi?id=2345043Issue Tracking
- https://seclists.org/oss-sec/2025/q1/144
- https://www.qualys.com/2025/02/18/openssh-mitm-dos.txtThird Party Advisory
- 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=1237041Third Party Advisory
- https://security-tracker.debian.org/tracker/CVE-2025-26466Third Party Advisory
- https://security.netapp.com/advisory/ntap-20250228-0002/Third Party Advisory
- https://ubuntu.com/security/CVE-2025-26466Third Party Advisory
- https://www.openwall.com/lists/oss-security/2025/02/18/1Mailing List, Third Party Advisory
- https://www.openwall.com/lists/oss-security/2025/02/18/4Mailing List, Third Party Advisory
- 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://cert-portal.siemens.com/productcert/html/ssa-398330.html
- https://www.qualys.com/2025/02/18/openssh-mitm-dos.txtThird Party Advisory
Source: NVD record, EPSS from FIRST.org, KEV from CISA, exploits from Exploit-DB. Refreshed daily. Download this record as JSON.