CVE-2016-20012

Name: CVE-2016-20012
Creator: NVD / NIST
Published: 2021-09-15T20:15:07.31+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

MEDIUMCVSS 5.3/10EPSS 5.04%

Last modified Jun 17, 2026

CVE-2016-20012 is a medium-severity vulnerability rated 5.3/10 on the CVSS scale. OpenSSH through 8.7 allows remote attackers, who have a suspicion that a certain combination of username and public key is known to an SSH server, to test whether this suspicion is correct. This occurs because a challenge is sent only when that combination could be valid for a login session. EPSS estimates a 5.04% chance of exploitation in the next 30 days.

Description

OpenSSH through 8.7 allows remote attackers, who have a suspicion that a certain combination of username and public key is known to an SSH server, to test whether this suspicion is correct. This occurs because a challenge is sent only when that combination could be valid for a login session. NOTE: the vendor does not recognize user enumeration as a vulnerability for this product

Metrics

CVSS 3.1

5.3/10

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

EPSS Probability

5.04%

91.2th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-203

Affected Software

Vendor	Product	Versions
Openbsd	Openssh	<= 8.7
Netapp	Clustered Data Ontap	All versions
Netapp	Hci Management Node	All versions
Netapp	Ontap Select Deploy Administration Utility	All versions
Netapp	Solidfire	All versions

References

https://github.com/openssh/openssh-portable/blob/d0fffc88c8fe90c1815c6f4097bc8cbcabc0f3dd/auth2-pubkey.c#L261-L265Exploit, Third Party Advisory
https://github.com/openssh/openssh-portable/pull/270Patch, Third Party Advisory
https://github.com/openssh/openssh-portable/pull/270#issuecomment-920577097Issue Tracking, Third Party Advisory
https://github.com/openssh/openssh-portable/pull/270#issuecomment-943909185Issue Tracking, Third Party Advisory
https://rushter.com/blog/public-ssh-keys/Exploit, Third Party Advisory
https://security.netapp.com/advisory/ntap-20211014-0005/Third Party Advisory
https://utcc.utoronto.ca/~cks/space/blog/tech/SSHKeysAreInfoLeakThird Party Advisory
https://www.openwall.com/lists/oss-security/2018/08/24/1Mailing List, Third Party Advisory
https://github.com/openssh/openssh-portable/blob/d0fffc88c8fe90c1815c6f4097bc8cbcabc0f3dd/auth2-pubkey.c#L261-L265Exploit, Third Party Advisory
https://github.com/openssh/openssh-portable/pull/270Patch, Third Party Advisory
https://github.com/openssh/openssh-portable/pull/270#issuecomment-920577097Issue Tracking, Third Party Advisory
https://github.com/openssh/openssh-portable/pull/270#issuecomment-943909185Issue Tracking, Third Party Advisory
https://rushter.com/blog/public-ssh-keys/Exploit, Third Party Advisory
https://security.netapp.com/advisory/ntap-20211014-0005/Third Party Advisory
https://utcc.utoronto.ca/~cks/space/blog/tech/SSHKeysAreInfoLeakThird Party Advisory
https://www.openwall.com/lists/oss-security/2018/08/24/1Mailing List, Third Party Advisory
https://github.com/openssh/openssh-portable/blob/d0fffc88c8fe90c1815c6f4097bc8cbcabc0f3dd/auth2-pubkey.c#L261-L265Exploit, Third Party Advisory

Timeline

Published: Sep 15, 2021
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2016-20012?

How severe is CVE-2016-20012?

CVE-2016-20012 has a CVSS score of 5.3/10 (MEDIUM severity). The EPSS model estimates a 5.04% probability of exploitation in the next 30 days.

How do I fix CVE-2016-20012?

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-2016-20012?

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

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Source: NVD / NIST