CVE-2023-51384

Severity: medium (CVSS 5.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.4% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2023-12-18 · updated 2026-10-15
Weakness: CWE-284

Description

In ssh-agent in OpenSSH before 9.6, certain destination constraints can be incompletely applied. When destination constraints are specified during addition of PKCS#11-hosted private keys, these constraints are only applied to the first key, even if a PKCS#11 token returns multiple keys.

Affected products

Debian Linux: 11.0, 12.0
OpenSSH: from 8.9 before 9.6 — fixed in 9.6

How to fix

Upgrade to a fixed version: OpenSSH 9.6. Check the vendor advisory for mitigations.

References

http://seclists.org/fulldisclosure/2024/Mar/21
https://github.com/openssh/openssh-portable/commit/881d9c6af9da4257c69c327c4e2f1508b2fa754b
https://security.netapp.com/advisory/ntap-20240105-0005/
https://support.apple.com/kb/HT214084
https://www.debian.org/security/2023/dsa-5586
https://www.openssh.com/txt/release-9.6
https://www.openwall.com/lists/oss-security/2023/12/18/2
http://seclists.org/fulldisclosure/2024/Mar/21
https://github.com/openssh/openssh-portable/commit/881d9c6af9da4257c69c327c4e2f1508b2fa754b
https://security.netapp.com/advisory/ntap-20240105-0005/
https://support.apple.com/kb/HT214084
https://www.debian.org/security/2023/dsa-5586

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