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.
Metrics
CVSS 3.1 5.9/10
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:HWeakness enumeration
Affected software
| Vendor | Product | Versions |
|---|---|---|
| — | — | >= 9.5p1, <= 9.9p1 |
| Red Hat | Red Hat Enterprise Linux 10 | — |
| Red Hat | Red Hat Enterprise Linux 9 | — |
| Red Hat | Red Hat Enterprise Linux 9 | — |
| Red Hat | Red Hat Enterprise Linux 6 | — |
| Red Hat | Red Hat Enterprise Linux 7 | — |
| Red Hat | Red Hat Enterprise Linux 8 | — |
| Red Hat | Red Hat OpenShift Container Platform 4 | — |
| Red Hat | Red Hat OpenShift Container Platform 4 | — |
| Siemens | SIMATIC S7-1500 CPU 1518-4 PN/DP MFP | >= V3.1.0, < V3.1.5 |
| Siemens | SIMATIC S7-1500 CPU 1518-4 PN/DP MFP | >= V3.1.0, < V3.1.5 |
| Siemens | SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP | >= V3.1.0, < V3.1.5 |
| Siemens | SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP | >= V3.1.0, < V3.1.5 |
| Siemens | SIPLUS S7-1500 CPU 1518-4 PN/DP MFP | >= V3.1.0, < V3.1.5 |
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
Timeline
- Published
- Feb 28, 2025
- Last modified
- Nov 5, 2026
- NVD status
- Modified