openssh: Public key information leak
Published Sep 15, 2021
5.9
MEDIUMCVSS 3.1
EPSS 5.33%
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
Affected products
No data.
Configuration 2
- n/a
- n/a
- n/a
- n/a
No data.
Red Hat Enterprise Linux 6
openssh
Not affected
Red Hat Enterprise Linux 7
openssh
Not affected
Red Hat Enterprise Linux 8
openssh
Not affected
Red Hat Enterprise Linux 9
openssh
Not affected
| Product | Package | State | Advisory |
|---|---|---|---|
| Red Hat Enterprise Linux 6 | openssh | Not affected | n/a |
| Red Hat Enterprise Linux 7 | openssh | Not affected | n/a |
| Red Hat Enterprise Linux 8 | openssh | Not affected | n/a |
| Red Hat Enterprise Linux 9 | openssh | Not affected | n/a |
No package ranges for this CVE.
Remediation
Red Hat statement
Although a CVE was assigned upstream and Red Hat doesn't consider it to be a security flaw and won't receive any patch, also the CVE was made as disputed by MITRE. Considering that Red Hat is closing this flaw as NOTABUG.
Metrics
No CVSS v4.0 score for this CVE.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
1 other source (Red Hat) ▾
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N
No CVSS v3.0 score for this CVE.
AV:N/AC:M/Au:N/C:P/I:N/A:N
This CVE is not in the KEV list.
CISA SSVC (Vulnrichment)
Stakeholder-Specific Vulnerability Categorization from CISA ADP.
Exploitation
NoneAutomatable
YesTechnical Impact
PartialDecision
n/aAssessed May 29, 2026 · SSVC 2.0.3
Estimated probability of exploitation in the wild in the next 30 days (FIRST EPSS). As of Oct 2, 2026.
Score over time
2022–2026- EPSS v2
- EPSS v3
- EPSS v4
- EPSS v5
Percentile over time
- EPSS v2
- EPSS v3
- EPSS v4
- EPSS v5
Table of values (37 key points)
Flat stretches are collapsed; showing up to 120 newest points.
| Date | Score | Percentile | Model |
|---|---|---|---|
| Oct 2, 2026 | 5.33% (0.05326) | 92.37th | v5 (v2026.06.15) |
| Jun 15, 2026 | 5.04% (0.05039) | 91.15th | v5 (v2026.06.15) |
| May 30, 2026 | 8.65% (0.08647) | 92.58th | v4 (v2025.03.14) |
| Dec 7, 2025 | 14.60% (0.14603) | 94.20th | v4 (v2025.03.14) |
| Dec 4, 2025 | 16.32% (0.16318) | 94.58th | v4 (v2025.03.14) |
| Dec 1, 2025 | 17.68% (0.17684) | 94.89th | v4 (v2025.03.14) |
| Nov 4, 2025 | 16.32% (0.16318) | 94.56th | v4 (v2025.03.14) |
| Nov 1, 2025 | 17.68% (0.17684) | 94.87th | v4 (v2025.03.14) |
| Oct 26, 2025 | 16.32% (0.16318) | 94.55th | v4 (v2025.03.14) |
| Oct 6, 2025 | 19.50% (0.19497) | 95.19th | v4 (v2025.03.14) |
| Oct 1, 2025 | 14.64% (0.14644) | 94.28th | v4 (v2025.03.14) |
| Sep 29, 2025 | 17.60% (0.17603) | 94.87th | v4 (v2025.03.14) |
| Sep 14, 2025 | 21.60% (0.21597) | 95.53th | v4 (v2025.03.14) |
| Jul 30, 2025 | 25.75% (0.25752) | 96.02th | v4 (v2025.03.14) |
| Jul 16, 2025 | 21.37% (0.21372) | 95.41th | v4 (v2025.03.14) |
| Jun 19, 2025 | 20.00% (0.20004) | 95.16th | v4 (v2025.03.14) |
| May 2, 2025 | 13.61% (0.13614) | 93.87th | v4 (v2025.03.14) |
| Mar 30, 2025 | 16.89% (0.16885) | 94.42th | v4 (v2025.03.14) |
| Mar 29, 2025 | 57.15% (0.57152) | 97.32th | v4 (v2025.03.14) |
| Mar 28, 2025 | 16.89% (0.16885) | 94.42th | v4 (v2025.03.14) |
| Mar 27, 2025 | 57.15% (0.57152) | 97.84th | v4 (v2025.03.14) |
| Mar 20, 2025 | 52.62% (0.52619) | 97.74th | v4 (v2025.03.14) |
| Mar 19, 2025 | 57.15% (0.57152) | 97.88th | v4 (v2025.03.14) |
| Mar 17, 2025 | 52.62% (0.52619) | 97.68th | v4 (v2025.03.14) |
| Dec 17, 2024 | 0.52% (0.00524) | 76.76th | v3 (v2023.03.01) |
| Aug 28, 2024 | 2.11% (0.02113) | 89.40th | v3 (v2023.03.01) |
| May 31, 2024 | 0.59% (0.00589) | 78.23th | v3 (v2023.03.01) |
| Apr 21, 2024 | 0.56% (0.00555) | 77.35th | v3 (v2023.03.01) |
| Feb 8, 2024 | 0.48% (0.00477) | 75.03th | v3 (v2023.03.01) |
| Dec 8, 2023 | 0.48% (0.00477) | 73.02th | v3 (v2023.03.01) |
| Apr 8, 2023 | 0.37% (0.00369) | 68.34th | v3 (v2023.03.01) |
| Mar 7, 2023 | 0.33% (0.00327) | 66.20th | v3 (v2023.03.01) |
| Mar 6, 2023 | 1.41% (0.01408) | 72.89th | v2 (v2022.01.01) |
| Mar 2, 2023 | 1.41% (0.01408) | 72.88th | v2 (v2022.01.01) |
| Apr 1, 2022 | 1.41% (0.01408) | 70.87th | v2 (v2022.01.01) |
| Feb 23, 2022 | 1.41% (0.01408) | 50.37th | v2 (v2022.01.01) |
| Feb 4, 2022 | 1.21% (0.01213) | 40.54th | v2 (v2022.01.01) |
References (12)
- https://access.redhat.com/security/cve/CVE-2016-20012 Vendor Advisory
- https://bugzilla.redhat.com/show_bug.cgi?id=2048523 Issue Tracking
- https://github.com/openssh/openssh-portable/blob/d0fffc88c8fe90c1815c6f4097bc8cbcabc0f3dd/auth2-pubkey.c#L261-L265 exploitx_refsource_MISCThird Party Advisory
- https://github.com/openssh/openssh-portable/pull/270 x_refsource_MISCPatchThird Party Advisory
- https://github.com/openssh/openssh-portable/pull/270#issuecomment-920577097 x_refsource_MISCIssue TrackingThird Party Advisory
- https://github.com/openssh/openssh-portable/pull/270#issuecomment-943909185 x_refsource_MISCIssue TrackingThird Party Advisory
- https://nvd.nist.gov/vuln/detail/CVE-2016-20012
- https://rushter.com/blog/public-ssh-keys/ x_refsource_MISCExploitThird Party Advisory
- https://security.netapp.com/advisory/ntap-20211014-0005/ x_refsource_CONFIRMThird Party Advisory
- https://utcc.utoronto.ca/~cks/space/blog/tech/SSHKeysAreInfoLeak x_refsource_MISCThird Party Advisory
- https://www.cve.org/CVERecord?id=CVE-2016-20012
- https://www.openwall.com/lists/oss-security/2018/08/24/1 x_refsource_MISCMailing ListThird Party Advisory
Change history (0)
No recorded changes yet.