CVE-2011-0539: OpenBSD OpenSSH

High severity, CVSS 7.5. EPSS: 1.8% chance of exploitation in the next 30 days.

The key_certify function in usr.bin/ssh/key.c in OpenSSH 5.6 and 5.7, when generating legacy certificates using the -t command-line option in ssh-keygen, does not initialize the nonce field, which might allow remote attackers to obtain sensitive stack memory contents or make it easier to conduct hash collision attacks.

Affected products

• OpenBSD OpenSSH: version 5.6 only; version 5.7 only

Published 2011-02-10. Last modified 2026-06-16.