CVERadar
MEDIUM · CVSS 3.1 6.8Public PoCEPSS 7.72% (p95)Threat level 40

CVE-2025-26465: CVE-2025-26465: A vulnerability was found in OpenSSH when the VerifyHostKeyDNS option is enabled. A machin…

openbsd · openssh · NVD published 2025-02-19 · posted 2025-02-18 · last modified 2026-11-05

CVE-2025-26465 at a glance

CVE-2025-26465 is a medium-severity vulnerability in Openbsd Openssh, with a CVSS 3.1 base score of 6.8. NVD published it on 2025-02-19 and classifies the weakness as CWE-390. Public exploit code: 2 public GitHub proof-of-concept repositories from 2 accounts, with the earliest exploit evidence dated 2025-02-18. FIRST EPSS puts the probability of exploitation activity in the next 30 days at 7.72% (percentile 94.6, scored 2026-11-09). NVD lists affected versions up to and including 9.8 for openbsd openssh but no fixed release; the vendor advisory has the fix. Its CVERadar threat level is 40/100.

What it is

A vulnerability was found in OpenSSH when the VerifyHostKeyDNS option is enabled. A machine-in-the-middle attack can be performed by a malicious machine impersonating a legit server. This issue occurs due to how OpenSSH mishandles error codes in specific conditions when verifying the host key. For an attack to be considered successful, the attacker needs to manage to exhaust the client's memory resource first, turning the attack complexity high.

WeaknessCWE-390 definition
CVSS vectorCVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:N (source: NIST NVD)
ATT&CK tacticsn/a

Exploitation evidence

First exploit evidence seen: 2025-02-18 (earliest date across the sources below).

Exploited in the wild

No source on this site lists in-the-wild exploitation yet (CISA KEV, VulnCheck KEV).

Public exploit code

GitHub proof-of-concept repositories

2 public repositories from 2 accounts, first seen 2025-02-18. Most starred: rxerium/CVE-2025-26465 (10 stars), view the rxerium/CVE-2025-26465 repository on GitHub.

Verify before running: public PoCs can be malicious. Read the code and only run it in an isolated lab. A PoC means exploit code is public, not that this CVE is exploited in the wild.

Sources: nomi-sec/PoC-in-GitHub.

Patches, mitigations and detection

Fixed versions

  • openbsd openssh: versions up to and including 9.8 are affected; check the vendor advisory for the fixed release.

Derived from the NVD CPE configuration (versionEndExcluding / versionEndIncluding). Always confirm with the vendor advisory.

Vendor advisories and patches

Detection Generic guidance

    Response checklist Generic guidance

    1. Inventory: find every instance of the affected product and version (include internet-facing and forgotten ones).
    2. Patch or mitigate per the vendor advisory; if you cannot patch, remove internet exposure or apply the vendor workaround.
    3. Assume compromise if the system was exposed before patching: hunt for the indicators in the advisory and review logs back to the disclosure date.
    4. Rotate credentials and secrets stored on or used by the affected system if compromise cannot be ruled out.

    For a hand keeping Openbsd Openssh hosts on supported, patched builds, see LayerLogix server maintenance.

    Sources