CVE-2025-26466
Openssh: denial-of-service in openssh
CVSS Score
5.9
EPSS Score
0.0%
EPSS Percentile
0th
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.
| CWE | CWE-770 |
| Published | Feb 28, 2025 |
| Last Updated | Feb 10, 2026 |
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CVSS v3 Breakdown
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H Attack Vector
Network
Attack Complexity
High
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High
Affected Versions
Red Hat / Red Hat Enterprise Linux 10
All versions affected Red Hat / Red Hat Enterprise Linux 6
All versions affected Red Hat / Red Hat Enterprise Linux 7
All versions affected Red Hat / Red Hat Enterprise Linux 8
All versions affected Red Hat / Red Hat Enterprise Linux 9
All versions affected Red Hat / Red Hat OpenShift Container Platform 4
All versions affected References
access.redhat.com: https://access.redhat.com/security/cve/CVE-2025-26466 bugzilla.redhat.com: https://bugzilla.redhat.com/show_bug.cgi?id=2345043 seclists.org: https://seclists.org/oss-sec/2025/q1/144 qualys.com: https://www.qualys.com/2025/02/18/openssh-mitm-dos.txt security.netapp.com: https://security.netapp.com/advisory/ntap-20250228-0002/ openwall.com: https://www.openwall.com/lists/oss-security/2025/02/18/1 openwall.com: https://www.openwall.com/lists/oss-security/2025/02/18/4 bugzilla.suse.com: https://bugzilla.suse.com/show_bug.cgi?id=1237041 security-tracker.debian.org: https://security-tracker.debian.org/tracker/CVE-2025-26466 ubuntu.com: https://ubuntu.com/security/CVE-2025-26466 seclists.org: http://seclists.org/fulldisclosure/2025/May/8 seclists.org: http://seclists.org/fulldisclosure/2025/May/7 seclists.org: http://seclists.org/fulldisclosure/2025/Feb/18 vicarius.io: https://www.vicarius.io/vsociety/posts/cve-2025-26466-detection-script-memory-consumption-vulnerability-in-openssh vicarius.io: https://www.vicarius.io/vsociety/posts/cve-2025-26466-mitigation-script-memory-consumption-vulnerability-in-openssh