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Vulnerabilities

Vulnerability · CVE-2025-26466

A flaw was found in the OpenSSH package.

Published Feb 28, 2025 · catalog updated Oct 15, 2026 · A flaw was found

Check this week

CVE-2025-26466 is not in CISA KEV. FIRST estimates a 40.65% chance of exploitation in the next 30 days. Check whether you run A flaw was found.

Gaps on this record

  • The stored product name is a package slug. The name on this page is taken from the title (A flaw was found).
  • No vendor fix or required action is stored. Compare the linked advisory before you change production.
Severity
Medium5.9
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
40.65%
Remediation
Advisory link
Affected products
cpe canonical/ubuntu linux · cpe debian/debian linux · cpe openbsd/openssh

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.

Are you affected?

Enter the version you run. The result uses only the ranges stored on this record.

The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.

  • cpe canonical/ubuntu linux24.04
  • cpe debian/debian linux11.0
  • cpe openbsd/openssh9.5
  • cpe openbsd/openssh9.6
  • cpe openbsd/openssh9.7
  • cpe openbsd/openssh9.8
  • cpe openbsd/openssh9.9

How to fix CVE-2025-26466

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

CVE-2025-26466 is not in CISA KEV. FIRST estimates a 40.65% chance of exploitation in the next 30 days. Check whether you run A flaw was found.

Which versions are affected?

Compare what you have installed with canonical/ubuntu linux 24.04; debian/debian linux 11.0. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

CWE-770: Allocation of Resources Without Limits or Throttling. EPSS 40.65%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Code

The project this record applies to. Exploit listings stay in References.

No public source repository is identified for this product.

Timeline

Detection, updates, and resolution for this record.

  1. Feb 28, 2025 · NIST NVD

    Detected

    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

  2. Oct 15, 2026 · NIST NVD

    Updated

    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

Sources

  • CVE.orgVulnerability recordCVE-2025-26466

    Official CVE identifier

    cve.org
  • FIRST EPSSExploitation probabilityCVE-2025-26466

    30-day exploitation probability 40.6%

    first.org
  • NIST NVDVulnerability recordCVE-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 pack

    nvd.nist.gov

References

Freshness

Last verified in this catalog Oct 16, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.