CVE-2025-26466Openssh: denial-of-service in openssh
Updated under an hour ago ()
Does this affect you?
It affects Red Hat Enterprise Linux 10 and 7 other products. Add what you run to find out whether that includes you.
No exploitation reported and no EPSS estimate yet.
Do this next
Free account, 1 product
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 MEDIUM (v3.1, CNA)CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
- Weakness (CWE)
- CWE-770
- Known exploited
- Not in CISA's KEV catalog
- EPSS (exploitation in the next 30 days)
- Not loaded for this CVE
- Assigned by
- redhat
- NVD analysis
- Modified
- Record last updated
- Oct 15, 2026
- First seen by InfoSec Signals
- Oct 9, 2026
Affected products
Red Hat Red Hat Enterprise Linux 10 redhat:enterprise_linux | from 0:9.9p1-7.el10_0 not affected | CNA record |
Red Hat Red Hat OpenShift Container Platform 4 redhat:openshift | 4 | CNA record |
Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP siemens:simatic_s7_1500_cpu_1518_4_pn_dp_mfp (from the name) | from V3.1.0 before V3.1.5 | CISA ADP |
Siemens SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP siemens:simatic_s7_1500_cpu_1518f_4_pn_dp_mfp (from the name) | from V3.1.0 before V3.1.5 | CISA ADP |
Siemens SIPLUS S7-1500 CPU 1518-4 PN/DP MFP siemens:siplus_s7_1500_cpu_1518_4_pn_dp_mfp (from the name) | from V3.1.0 before V3.1.5 | CISA ADP |
openbsd openssh openbsd:openssh | 9.5; 9.6; 9.6; 9.7; 9.7; 9.8; 9.8; 9.9; and 1 more ranges | NVD |
canonical ubuntu_linux canonical:ubuntu_linux | 24.04; 24.10 | NVD |
debian debian_linux debian:debian_linux | 11.0; 12.0; 13.0 | NVD |
References
- https://access.redhat.com/errata/RHBA-2025:6305vendor-advisory, x-refsource-redhat
- https://access.redhat.com/errata/RHSA-2025:6993vendor-advisory, x-refsource-redhat
- https://access.redhat.com/security/cve/CVE-2025-26466vdb-entry, x-refsource-redhat, third-party-advisory
- https://bugzilla.redhat.com/show_bug.cgi?id=2345043issue-tracking, x-refsource-redhat
- 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
The CVE record on cve.org NVD's entry
The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.