openssh: User enumeration via covert timing channel
Published Feb 13, 2017
5.9
MEDIUMCVSS 3.1
EPSS 88.94%
Description
sshd in OpenSSH before 7.3, when SHA256 or SHA512 are used for user password hashing, uses BLOWFISH hashing on a static password when the username does not exist, which allows remote attackers to enumerate users by leveraging the timing difference between responses when a large password is provided.
Affected products
No data.
No data.
Red Hat Enterprise Linux 6
openssh-0:5.3p1-123.el6_9
Fixed · RHSA-2017:2563
Red Hat Enterprise Linux 7
openssh-0:7.4p1-11.el7
Fixed · RHSA-2017:2029
Red Hat Enterprise Linux 5
openssh
Will not fix
| Product | Package | State | Advisory |
|---|---|---|---|
| Red Hat Enterprise Linux 6 | openssh-0:5.3p1-123.el6_9 | Fixed | RHSA-2017:2563 |
| Red Hat Enterprise Linux 7 | openssh-0:7.4p1-11.el7 | Fixed | RHSA-2017:2029 |
| Red Hat Enterprise Linux 5 | openssh | Will not fix | n/a |
No package ranges for this CVE.
Remediation
Red Hat statement
This issue in OpenSSH is mitigated by the usage of SELinux in Red Hat Enterprise Linux 6 and Red Hat Enterprise Linux 7.
Metrics
No CVSS v4.0 score for this CVE.
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N
CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N
1 other source (Red Hat) ▾
CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
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
PoCAutomatable
NoTechnical 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 1, 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 (14 key points)
Flat stretches are collapsed; showing up to 120 newest points.
| Date | Score | Percentile | Model |
|---|---|---|---|
| Oct 1, 2026 | 88.94% (0.88944) | 99.78th | v5 (v2026.06.15) |
| Jun 15, 2026 | 88.94% (0.88944) | 99.76th | v5 (v2026.06.15) |
| Apr 22, 2026 | 90.05% (0.90046) | 99.59th | v4 (v2025.03.14) |
| Mar 28, 2025 | 92.49% (0.92487) | 99.73th | v4 (v2025.03.14) |
| Mar 24, 2025 | 91.37% (0.91372) | 99.66th | v4 (v2025.03.14) |
| Mar 23, 2025 | 92.49% (0.92487) | 99.73th | v4 (v2025.03.14) |
| Mar 20, 2025 | 91.37% (0.91372) | 99.66th | v4 (v2025.03.14) |
| Mar 19, 2025 | 92.49% (0.92487) | 99.73th | v4 (v2025.03.14) |
| Mar 17, 2025 | 91.37% (0.91372) | 99.65th | v4 (v2025.03.14) |
| Dec 17, 2024 | 6.88% (0.06884) | 93.84th | v3 (v2023.03.01) |
| Dec 12, 2024 | 10.67% (0.10667) | 95.32th | v3 (v2023.03.01) |
| Mar 7, 2023 | 10.74% (0.10737) | 94.11th | v3 (v2023.03.01) |
| Mar 6, 2023 | 49.18% (0.49183) | 98.65th | v2 (v2022.01.01) |
| Feb 4, 2022 | 49.18% (0.49183) | 98.17th | v2 (v2022.01.01) |
References (16)
- http://seclists.org/fulldisclosure/2016/Jul/51 mailing-listMailing ListThird Party Advisory
- http://www.debian.org/security/2016/dsa-3626 vendor-advisory
- http://www.securityfocus.com/bid/91812 vdb-entryThird Party AdvisoryVDB Entry
- http://www.securitytracker.com/id/1036319 vdb-entry
- https://access.redhat.com/errata/RHSA-2017:2029 vendor-advisory
- https://access.redhat.com/errata/RHSA-2017:2563 vendor-advisory
- https://access.redhat.com/security/cve/CVE-2016-6210 Vendor Advisory
- https://bugzilla.redhat.com/show_bug.cgi?id=1357442 Issue Tracking
- https://cert-portal.siemens.com/productcert/pdf/ssa-412672.pdf
- https://nvd.nist.gov/vuln/detail/CVE-2016-6210
- https://security.gentoo.org/glsa/201612-18 vendor-advisory
- https://security.netapp.com/advisory/ntap-20190206-0001/
- https://www.cve.org/CVERecord?id=CVE-2016-6210
- https://www.exploit-db.com/exploits/40113/ exploit
- https://www.exploit-db.com/exploits/40136/ exploit
- https://www.openssh.com/txt/release-7.3 Release NotesVendor Advisory
| Link | Providers | Tags |
|---|---|---|
| http://seclists.org/fulldisclosure/2016/Jul/51 | mailing-listMailing ListThird Party Advisory | |
| http://www.debian.org/security/2016/dsa-3626 | vendor-advisory | |
| http://www.securityfocus.com/bid/91812 | vdb-entryThird Party AdvisoryVDB Entry | |
| http://www.securitytracker.com/id/1036319 | vdb-entry | |
| https://access.redhat.com/errata/RHSA-2017:2029 | vendor-advisory | |
| https://access.redhat.com/errata/RHSA-2017:2563 | vendor-advisory | |
| https://access.redhat.com/security/cve/CVE-2016-6210 | Vendor Advisory | |
| https://bugzilla.redhat.com/show_bug.cgi?id=1357442 | Issue Tracking | |
| https://cert-portal.siemens.com/productcert/pdf/ssa-412672.pdf | ||
| https://nvd.nist.gov/vuln/detail/CVE-2016-6210 | ||
| https://security.gentoo.org/glsa/201612-18 | vendor-advisory | |
| https://security.netapp.com/advisory/ntap-20190206-0001/ | ||
| https://www.cve.org/CVERecord?id=CVE-2016-6210 | ||
| https://www.exploit-db.com/exploits/40113/ | exploit | |
| https://www.exploit-db.com/exploits/40136/ | exploit | |
| https://www.openssh.com/txt/release-7.3 | Release NotesVendor Advisory |
Change history (0)
No recorded changes yet.