CVE-2025-26465
Openssh: machine-in-the-middle attack if verifyhostkeydns is enabled
- Published
- Feb 18, 2025
- Updated
- Sep 2, 2026
- Assigning CNA
- redhat
- Evidence observed
- Aug 8, 2026
Primary CVSS
nvd · CVSS 3.1
CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:NLow · next 30 days
- Percentile
- 94.4%
- Model date
- Sep 21, 2026
EPSS is a statistical estimate, not a certainty or a measure of impact. Combine it with CVSS, KEV status, exposure and your environment.
Summary
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.
Sources
2Patch Manual para a correção das CVE-2025-26465-e-CVE-2025-26466, para sistemas sem update do OpenSSH
- CVE-2025-26465Detection
MitM attack allowing a malicious interloper to impersonate a legitimate server when a client attempts to connect to it
Responsible use
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