CVE-2025-26466

Openssh: denial-of-service in openssh

MEDIUM
5.9
CVSS Score
Published: February 28, 2025 at 09:25 PM UTC
Updated: October 21, 2026 at 05:17 PM UTC
5 products affected across 4 vendorsDebian LinuxUbuntu LinuxOpenSSH

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Severity
MEDIUM5.9
Exploit prediction
EPSS 39%
SSVC
PoC

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.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

All versions
Vendor states this is fixed in 0:8.7p1-45.el9 (unaffected)
Vendor states this is fixed in 0:9.9p1-7.el10_0 (unaffected)
Vendor states this is fixed in 10 (unaffected)
Vendor states this is fixed in 6 (unaffected)
Vendor states this is fixed in 7 (unaffected)
Vendor states this is fixed in 8 (unaffected)
Vendor states this is fixed in 9 (unaffected)
All versions
Vendor states this is fixed in 4 (unaffected)

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

References (18)

VDB Entryx_refsource_REDHATThird Party Advisory
https://access.redhat.com/security/cve/CVE-2025-26466
Third Party Advisory
Source: af854a3a-2127-422b-91ae-364da2661108
https://bugzilla.suse.com/show_bug.cgi?id=1237041
Third Party Advisory
Source: af854a3a-2127-422b-91ae-364da2661108
https://security-tracker.debian.org/tracker/CVE-2025-26466
Third Party Advisory
Source: af854a3a-2127-422b-91ae-364da2661108
https://security.netapp.com/advisory/ntap-20250228-0002/
Third Party Advisory
Source: af854a3a-2127-422b-91ae-364da2661108
https://ubuntu.com/security/CVE-2025-26466

SSVC — Action Prioritization

SSVCPoCNot automatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

5.9MEDIUMredhat
Attack Vector
NETWORK
Complexity
HIGH
Privileges
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
NONE
Integrity
NONE
Availability
HIGH
Vector?

Quick Info

StatusMODIFIED
CWE
CWE-770

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