HIGH
openssh: Denial of service via very long passwords
Published Aug 7, 2016
7.5
HIGHCVSS 3.0
EPSS 58.57%
Description
The auth_password function in auth-passwd.c in sshd in OpenSSH before 7.3 does not limit password lengths for password authentication, which allows remote attackers to cause a denial of service (crypt CPU consumption) via a long string.
Affected products
No data.
Configuration 2
- 24
No data.
Red Hat Enterprise Linux 7
openssh-0:7.4p1-11.el7
Fixed · RHSA-2017:2029
Red Hat Enterprise Linux 5
openssh
Will not fix
Red Hat Enterprise Linux 6
openssh
Will not fix
| Product | Package | State | Advisory |
|---|---|---|---|
| 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 |
| Red Hat Enterprise Linux 6 | 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, 7 and 8. More details available at: https://bugzilla.redhat.com/show_bug.cgi?id=1364935#c13
Metrics
No CVSS v4.0 score for this CVE.
No CVSS v3.1 score for this CVE.
7.5 HIGH NVD
CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Attack Vector Network
Attack Complexity Low
Privileges Required None
User Interaction None
Scope Unchanged
Confidentiality Impact None
Integrity Impact None
Availability Impact High
1 other source (Red Hat) ▾
5.3 MEDIUM Red Hat
CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
Attack Vector Network
Attack Complexity Low
Privileges Required None
User Interaction None
Scope Unchanged
Confidentiality Impact None
Integrity Impact None
Availability Impact Low
7.8 HIGH NVD
AV:N/AC:L/Au:N/C:N/I:N/A:C
Access Vector Network
Access Complexity Low
Authentication None
Confidentiality Impact None
Integrity Impact None
Availability Impact Complete
This CVE is not in the KEV list.
No CISA SSVC assessment for this CVE yet.
58.57% 0.58568
Estimated probability of exploitation in the wild in the next 30 days (FIRST EPSS). As of Oct 1, 2026.
EPSS probability 0.58568
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 (59 key points)
Flat stretches are collapsed; showing up to 120 newest points.
| Date | Score | Percentile | Model |
|---|---|---|---|
| Oct 1, 2026 | 58.57% (0.58568) | 99.08th | v5 (v2026.06.15) |
| Sep 22, 2026 | 58.57% (0.58568) | 99.06th | v5 (v2026.06.15) |
| Sep 21, 2026 | 46.16% (0.46160) | 98.80th | v5 (v2026.06.15) |
| Sep 6, 2026 | 58.57% (0.58568) | 99.04th | v5 (v2026.06.15) |
| Sep 5, 2026 | 46.16% (0.46160) | 98.77th | v5 (v2026.06.15) |
| Aug 30, 2026 | 58.57% (0.58568) | 99.03th | v5 (v2026.06.15) |
| Aug 28, 2026 | 46.16% (0.46160) | 98.76th | v5 (v2026.06.15) |
| Aug 24, 2026 | 58.57% (0.58568) | 99.03th | v5 (v2026.06.15) |
| Aug 23, 2026 | 46.16% (0.46160) | 98.76th | v5 (v2026.06.15) |
| Jun 15, 2026 | 57.67% (0.57667) | 98.96th | v5 (v2026.06.15) |
| May 27, 2026 | 77.09% (0.77091) | 98.99th | v4 (v2025.03.14) |
| May 2, 2026 | 75.79% (0.75794) | 98.92th | v4 (v2025.03.14) |
| Apr 5, 2026 | 81.62% (0.81624) | 99.18th | v4 (v2025.03.14) |
| Mar 4, 2026 | 84.41% (0.84415) | 99.30th | v4 (v2025.03.14) |
| Mar 1, 2026 | 86.40% (0.86398) | 99.40th | v4 (v2025.03.14) |
| Feb 4, 2026 | 84.41% (0.84415) | 99.30th | v4 (v2025.03.14) |
| Feb 1, 2026 | 86.40% (0.86398) | 99.40th | v4 (v2025.03.14) |
| Jan 4, 2026 | 84.41% (0.84415) | 99.29th | v4 (v2025.03.14) |
| Jan 1, 2026 | 86.40% (0.86398) | 99.39th | v4 (v2025.03.14) |
| Dec 28, 2025 | 84.41% (0.84415) | 99.28th | v4 (v2025.03.14) |
| Dec 27, 2025 | 82.90% (0.82903) | 99.22th | v4 (v2025.03.14) |
| Dec 4, 2025 | 84.41% (0.84415) | 99.27th | v4 (v2025.03.14) |
| Dec 1, 2025 | 86.40% (0.86398) | 99.38th | v4 (v2025.03.14) |
| Nov 4, 2025 | 84.41% (0.84415) | 99.27th | v4 (v2025.03.14) |
| Nov 1, 2025 | 86.40% (0.86398) | 99.37th | v4 (v2025.03.14) |
| Oct 28, 2025 | 84.41% (0.84415) | 99.27th | v4 (v2025.03.14) |
| Oct 27, 2025 | 82.90% (0.82903) | 99.20th | v4 (v2025.03.14) |
| Oct 4, 2025 | 84.41% (0.84415) | 99.28th | v4 (v2025.03.14) |
| Oct 1, 2025 | 86.40% (0.86398) | 99.38th | v4 (v2025.03.14) |
| Sep 4, 2025 | 82.90% (0.82903) | 99.21th | v4 (v2025.03.14) |
| Sep 1, 2025 | 85.17% (0.85175) | 99.33th | v4 (v2025.03.14) |
| Aug 20, 2025 | 82.90% (0.82903) | 99.20th | v4 (v2025.03.14) |
| Aug 4, 2025 | 79.87% (0.79870) | 99.06th | v4 (v2025.03.14) |
| Aug 1, 2025 | 82.28% (0.82279) | 99.17th | v4 (v2025.03.14) |
| Jul 30, 2025 | 79.87% (0.79870) | 99.05th | v4 (v2025.03.14) |
| Jul 24, 2025 | 81.75% (0.81753) | 99.13th | v4 (v2025.03.14) |
| Jul 4, 2025 | 75.97% (0.75974) | 98.85th | v4 (v2025.03.14) |
| Jul 1, 2025 | 78.96% (0.78961) | 99.00th | v4 (v2025.03.14) |
| Jun 19, 2025 | 75.97% (0.75974) | 98.84th | v4 (v2025.03.14) |
| Jun 4, 2025 | 84.41% (0.84415) | 99.26th | v4 (v2025.03.14) |
| Jun 1, 2025 | 86.40% (0.86398) | 99.37th | v4 (v2025.03.14) |
| May 4, 2025 | 84.41% (0.84415) | 99.25th | v4 (v2025.03.14) |
| May 1, 2025 | 86.40% (0.86398) | 99.36th | v4 (v2025.03.14) |
| Mar 30, 2025 | 84.41% (0.84415) | 99.27th | v4 (v2025.03.14) |
| Mar 29, 2025 | 87.74% (0.87741) | 99.35th | v4 (v2025.03.14) |
| Mar 28, 2025 | 84.41% (0.84415) | 99.27th | v4 (v2025.03.14) |
| Mar 27, 2025 | 87.74% (0.87741) | 99.43th | v4 (v2025.03.14) |
| Mar 20, 2025 | 84.41% (0.84415) | 99.31th | v4 (v2025.03.14) |
| Mar 19, 2025 | 87.74% (0.87741) | 99.44th | v4 (v2025.03.14) |
| Mar 17, 2025 | 84.61% (0.84607) | 99.29th | v4 (v2025.03.14) |
| Dec 17, 2024 | 3.47% (0.03466) | 91.36th | v3 (v2023.03.01) |
| Aug 12, 2024 | 4.50% (0.04500) | 92.58th | v3 (v2023.03.01) |
| Aug 11, 2024 | 16.60% (0.16599) | 96.10th | v3 (v2023.03.01) |
| Feb 20, 2024 | 4.50% (0.04500) | 92.17th | v3 (v2023.03.01) |
| Nov 8, 2023 | 4.53% (0.04532) | 91.57th | v3 (v2023.03.01) |
| May 8, 2023 | 4.48% (0.04483) | 91.19th | v3 (v2023.03.01) |
| Mar 7, 2023 | 3.11% (0.03111) | 89.53th | v3 (v2023.03.01) |
| Mar 6, 2023 | 47.64% (0.47641) | 98.58th | v2 (v2022.01.01) |
| Feb 4, 2022 | 47.64% (0.47641) | 98.07th | v2 (v2022.01.01) |
References (19)
- http://openwall.com/lists/oss-security/2016/08/01/2 mailing-listThird Party AdvisoryVDB Entry
- http://packetstormsecurity.com/files/140070/OpenSSH-7.2-Denial-Of-Service.html
- http://www.oracle.com/technetwork/security-advisory/cpuoct2017-3236626.html
- http://www.securityfocus.com/bid/92212 vdb-entry
- http://www.securitytracker.com/id/1036487 vdb-entry
- https://access.redhat.com/errata/RHSA-2017:2029 vendor-advisory
- https://access.redhat.com/security/cve/CVE-2016-6515 Vendor Advisory
- https://bugzilla.redhat.com/show_bug.cgi?id=1364935 Issue Tracking
- https://cert-portal.siemens.com/productcert/pdf/ssa-412672.pdf
- https://cert-portal.siemens.com/productcert/pdf/ssa-676336.pdf
- https://github.com/openssh/openssh-portable/commit/fcd135c9df440bcd2d5870405ad3311743d78d97 Issue TrackingPatch
- https://lists.debian.org/debian-lts-announce/2018/09/msg00010.html mailing-list
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/X2L6RW34VFNXYNVVN2CN73YAGJ5VMTFU/ vendor-advisory
- https://nvd.nist.gov/vuln/detail/CVE-2016-6515
- https://security.FreeBSD.org/advisories/FreeBSD-SA-17:06.openssh.asc vendor-advisory
- https://security.netapp.com/advisory/ntap-20171130-0003/
- https://support.hpe.com/hpsc/doc/public/display?docLocale=en_US&docId=emr_na-hpesbhf03779en_us
- https://www.cve.org/CVERecord?id=CVE-2016-6515
- https://www.exploit-db.com/exploits/40888/ exploit
Change history (0)
No recorded changes yet.
Sources
CVE.org / MITRE
Status PUBLISHED
Assigner mitre
Published Aug 7, 2016
Updated Aug 6, 2024
Reserved Aug 1, 2016
Link CVE-2016-6515
CISA Vulnrichment
Updated n/a