CVE-2011-0539

Name: CVE-2011-0539
Creator: NVD / NIST
Published: 2011-02-10T18:00:57.66+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

HIGHCVSS 7.5/10EPSS 1.80%

Last modified Jun 16, 2026

CVE-2011-0539 is a high-severity vulnerability rated 7.5/10 on the CVSS scale. 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.. EPSS estimates a 1.80% chance of exploitation in the next 30 days.

Description

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.

Metrics

CVSS 3.1

7.5/10

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

EPSS Probability

1.80%

75.6th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

Vendor	Product	Versions
Openbsd	Openssh	5.6
Openbsd	Openssh	5.7

References

Timeline

Published: Feb 10, 2011
Last Modified: Jun 16, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2011-0539?

How severe is CVE-2011-0539?

CVE-2011-0539 has a CVSS score of 7.5/10 (HIGH severity). The EPSS model estimates a 1.80% probability of exploitation in the next 30 days.

How do I fix CVE-2011-0539?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2011-0539?

Run a free Strix scan to check your systems for this vulnerability.

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Source: NVD / NIST