Resource exhaustion in Openbsd Openssh
CVE-2025-26466
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.
EPSS: 0.396 (98.5th percentile) — read the EPSS interpretation.
CVSS v3 metric
CVSS v3 base score 5.9 (Medium). Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H.
Affected products
- Openbsd Openssh — versions 9.5, 9.6, 9.7
- Canonical Ubuntu_linux — versions 24.04, 24.10
- Debian Debian_linux — versions 11.0, 12.0, 13.0
- Red Hat Enterprise Linux 10
- Red Hat Enterprise Linux 6
- Red Hat Enterprise Linux 7
- Red Hat Enterprise Linux 8
- Red Hat Enterprise Linux 9
- Red Hat In-vehicle Operating System 1
- Red Hat Openshift Container Platform 4
Weakness classification (CWE)
Public proof-of-concept exploits
- rxerium/CVE-2025-26466
- acidboonrs/cve-2025-26466-openssh-poc
- tpirate/CVE-2025-26466
- mrowkoob/CVE-2025-26466-msf
- Theshield-crack/wazuh-SIEM-with-ubuntu
- Theshield-crack/wazuh-SIEM-with-ubuntu-
- dolutech/patch-manual-CVE-2025-26465-e-CVE-2025-26466
- mosaicwang/myrpm
- nomi-sec/PoC-in-GitHub
- pawan-shivarkar/List-of-CVE-s-
References
- secalert@redhat.com (x_refsource_REDHAT, Third Party Advisory, vdb-entry)
- secalert@redhat.com (x_refsource_REDHAT, issue-tracking, Issue Tracking)
- secalert@redhat.com
- secalert@redhat.com (Third Party Advisory)
- af854a3a-2127-422b-91ae-364da2661108
- af854a3a-2127-422b-91ae-364da2661108
- af854a3a-2127-422b-91ae-364da2661108
- af854a3a-2127-422b-91ae-364da2661108 (Third Party Advisory)
- af854a3a-2127-422b-91ae-364da2661108 (Third Party Advisory)
- af854a3a-2127-422b-91ae-364da2661108 (Third Party Advisory)
Frequently asked questions
- What is CVE-2025-26466?
- CVE-2025-26466 is a medium-severity vulnerability in Openbsd Openssh, classified under Allocation of Resources Without Limits or Throttling. CVSS score: 5.9/10. Published 2025-02-28.
- How severe is CVE-2025-26466?
- Medium severity. CVSS v3 base score is 5.9 out of 10.
- Is CVE-2025-26466 known to be exploited?
- 15 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.