# CVE-2011-0539

## Summary

- **CVE ID:** CVE-2011-0539
- **Severity:** HIGH
- **CVSS Score:** 7.5 (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N)
- **CWE:** N/A
- **Published:** Feb 10, 2011
- **Last Modified:** May 29, 2026

## 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.

## Affected Products

- n/a — n/a (n/a)

## References

- [CNA](http://www.openwall.com/lists/oss-security/2011/02/04/2)
- [CNA](http://www.securitytracker.com/id?1025028)
- [CNA](http://www.securityfocus.com/bid/46155)
- [CNA](http://kb.juniper.net/InfoCenter/index?page=content&id=JSA10673)
- [CNA](http://www.vupen.com/english/advisories/2011/0284)
- [CNA](http://secunia.com/advisories/43181)
- [CNA](http://h20000.www2.hp.com/bizsupport/TechSupport/Document.jsp?objectID=c02794777)
- [CNA](http://secunia.com/advisories/44269)
- [CNA](http://www.openssh.com/txt/legacy-cert.adv)
- [CNA](https://exchange.xforce.ibmcloud.com/vulnerabilities/65163)

## Exploitation Prediction (EPSS)

- **EPSS Score:** 1.72%
- **EPSS Percentile:** 82.1

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_Exported from OnDuty AI Vulnerability Intelligence on 2026-09-17._