HOMEVULNERABILITIESCVE-2016-20012
MEDIUM

CVE-2016-20012

NVD-CWE-OtherPublished: September 15, 2021· Updated: Jun 17, 2026

5.3
CVSS v3.1

Official 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

NVD Source

Technical Analysis

CVE-2016-20012 can be exploited remotely over the network without requiring physical or adjacent access, significantly expanding the attack surface for threat actors.

The vulnerability requires no privileges and no user interaction, making it a prime target for automated exploitation campaigns and worm-like propagation.

CVSS v3.1 Vector Breakdown

Exploitability
Attack VectorNetwork
Attack ComplexityLow
Privileges Req.None
User InteractionNone
ScopeUnchanged
Impact
ConfidentialityLow
IntegrityNone
AvailabilityNone
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N

Affected Vendors & Products

netapp4 product(s)
clustered data ontaphci management nodeontap select deploy administration utilitysolidfire
openbsd1 product(s)
openssh
Source: NVD CPE · 5 total CPE entries

Exploit & PoC Resources

NO KNOWN EXPLOITNo public exploit confirmed at this time
Exploit-DB
Offensive Security exploit database
GitHub PoC Search
Community PoC repositories
Rapid7 / Metasploit
Metasploit module search
PacketStorm
Security advisories & exploits
NVD Detail
Official NIST entry
MITRE CVE
CVE Program entry
External links open in a new tab. Always verify in a controlled environment before use.

Official Patches & Advisories

PATCHhttps://github.com/openssh/openssh-portable/pull/270
PATCHhttps://github.com/openssh/openssh-portable/pull/270
ADVISORYhttps://github.com/openssh/openssh-portable/blob/d0fffc88c8fe90c1815c6f4097bc8cbcabc0f3dd/auth2-pubkey.c#L261-L265
ADVISORYhttps://github.com/openssh/openssh-portable/pull/270#issuecomment-920577097
ADVISORYhttps://github.com/openssh/openssh-portable/pull/270#issuecomment-943909185
ADVISORYhttps://rushter.com/blog/public-ssh-keys/
ADVISORYhttps://security.netapp.com/advisory/ntap-20211014-0005/
ADVISORYhttps://utcc.utoronto.ca/~cks/space/blog/tech/SSHKeysAreInfoLeak
ADVISORYhttps://www.openwall.com/lists/oss-security/2018/08/24/1
ADVISORYhttps://github.com/openssh/openssh-portable/blob/d0fffc88c8fe90c1815c6f4097bc8cbcabc0f3dd/auth2-pubkey.c#L261-L265
ADVISORYhttps://github.com/openssh/openssh-portable/pull/270#issuecomment-920577097
ADVISORYhttps://github.com/openssh/openssh-portable/pull/270#issuecomment-943909185
ADVISORYhttps://rushter.com/blog/public-ssh-keys/
ADVISORYhttps://security.netapp.com/advisory/ntap-20211014-0005/
ADVISORYhttps://utcc.utoronto.ca/~cks/space/blog/tech/SSHKeysAreInfoLeak
ADVISORYhttps://www.openwall.com/lists/oss-security/2018/08/24/1
ADVISORYhttps://github.com/openssh/openssh-portable/blob/d0fffc88c8fe90c1815c6f4097bc8cbcabc0f3dd/auth2-pubkey.c#L261-L265

All References (17)

→
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

Quick Facts

CVE IDCVE-2016-20012
CVSS Score5.3 / 10
SeverityMEDIUM
WeaknessNVD-CWE-Other
CISA KEVNo
Affected2 vendor(s)
PublishedSep 15, 2021

Related CVEs (NVD-CWE-Other)

CVE-1999-0913
10.0
CVE-2006-5972
10.0
CVE-1999-0208
10.0
CVE-1999-0791
10.0
CVE-2007-1435
10.0
CVE-2005-2277
10.0

Recommended Actions

  • →Apply vendor patches immediately
  • →Monitor CVE-2016-20012 in threat intel feeds
  • →Review IDS/IPS signatures for exploitation attempts
Data sourced from NVD (NIST), CISA KEV, and EPSS (FIRST). Analysis generated by CTIWatch. CVE data is provided under the NVD usage policy.
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