CVE-2025-26466
Openssh: denial-of-service in openssh
- State
- Published
- Severity
- 5.9 Medium
- Published
- Feb 28, 2025
- Updated
- Oct 21, 2026
- Reserved
- Feb 10, 2025
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.
Scores
| CVSS | Score | Vector | Source |
|---|---|---|---|
| 3.1 | 5.9 Medium | CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H | redhat |
Weaknesses
- CWE-770 Allocation of Resources Without Limits or Throttling
Affected Products
| Product | Versions |
|---|---|
OpenSSH |
|
Red Hat Enterprise Linux 10Red Hat |
|
Red Hat Enterprise Linux 9Red Hat |
|
Red Hat Enterprise Linux 9Red Hat |
|
Red Hat Enterprise Linux 6Red Hat | |
Red Hat Enterprise Linux 7Red Hat | |
Red Hat Enterprise Linux 8Red Hat | |
Red Hat OpenShift Container Platform 4Red Hat | |
Red Hat OpenShift Container Platform 4Red Hat |
References
- RHBA-2025:6305vendor-advisory
- RHSA-2025:6993vendor-advisory
- https://access.redhat.com/security/cve/CVE-2025-26466vdb-entry
- RHBZ#2345043issue-tracking
- https://seclists.org/oss-sec/2025/q1/144
- https://www.qualys.com/2025/02/18/openssh-mitm-dos.txt
- https://security.netapp.com/advisory/ntap-20250228-0002/
- https://www.openwall.com/lists/oss-security/2025/02/18/1
- https://www.openwall.com/lists/oss-security/2025/02/18/4
- https://bugzilla.suse.com/show_bug.cgi?id=1237041
- https://security-tracker.debian.org/tracker/CVE-2025-26466
- https://ubuntu.com/security/CVE-2025-26466
- http://seclists.org/fulldisclosure/2025/May/8
- http://seclists.org/fulldisclosure/2025/May/7
- http://seclists.org/fulldisclosure/2025/Feb/18
- 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
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