CVE-2025-26466
What it is
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.
At a glance
- Exploitability
- Can be exploited over the network without logging in. High risk of service disruption.
- Exploit odds
- 38.7% chance of exploitation in the next 30 days (EPSS). Higher than most.
- Fix
- No patch or advisory is linked yet. Look at mitigations or restrict exposure.
Timeline
- PublishedDisclosed publicly on CVE.org and NVD
- Last updatedMost recent change to the record
Why it ranks here
- Exploited in the wild: no, CISA does not list it.
- Exploit odds: 38.7% in the next 30 days (EPSS).
- Severity: 5.9 MEDIUM (CVSS).
- Fix: none linked yet, which raises it.
Details
- Published
- Last modified
- Exploit probability
- 38.7% · EPSS, next 30 days
- Weakness
- CWE-770 · Allocation without limits
- Record status
- Modified
Affected
- Openbsd OpenSSH 9.5
- Openbsd OpenSSH 9.6
- Openbsd OpenSSH 9.7
- Openbsd OpenSSH 9.8
- Openbsd OpenSSH 9.9
- Canonical Ubuntu Linux 24.04
- Canonical Ubuntu Linux 24.10
- Debian Linux 11.0
Attack profile CVSS 3.1 · 5.9
- Attack vector
- Network
- Complexity
- High
- Privileges needed
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- None
- Integrity
- None
- Availability
- High
Raw vector
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
Is it in your code?
Hand this to your coding agent. It searches your project for the affected products and checks versions. Nothing leaves your machine.
Read https://cve-list.com/agent/cve/CVE-2025-26466.md and follow it. Check whether this project is affected by CVE-2025-26466. Read only. Don't change anything and don't upload my code. Tell me yes, no or not sure, with the file as proof.
References
- https://access.redhat.com/errata/RHBA-2025:6305
- https://access.redhat.com/errata/RHSA-2025:6993
- https://access.redhat.com/security/cve/CVE-2025-26466
- https://bugzilla.redhat.com/show_bug.cgi?id=2345043
- https://seclists.org/oss-sec/2025/q1/144
- https://www.qualys.com/2025/02/18/openssh-mitm-dos.txt
- 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=1237041
- https://security-tracker.debian.org/tracker/CVE-2025-26466
- https://security.netapp.com/advisory/ntap-20250228-0002/
- https://ubuntu.com/security/CVE-2025-26466
- https://www.openwall.com/lists/oss-security/2025/02/18/1
- https://www.openwall.com/lists/oss-security/2025/02/18/4
- 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.txt