CVE-2025-26465
MediumCVSS 6.8Exploitation Probability (EPSS)
Very high risk93th percentile - higher than 93% of all known CVEs
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.
Risk Assessment
The risk involves potential interception and modification of SSH communication by an attacker, which could lead to data theft or unauthorized access. However, the attack requires prior exhaustion of the client's memory, increasing its complexity.
Recommendation
It is recommended to disable the VerifyHostKeyDNS option in the SSH client configuration if not needed, and update OpenSSH to the latest version after a patch is released.
Original NVD description (English source)
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.