krb5: Authentication bypass by improper validation of certificate EKU and SAN
Published Jul 26, 2018
6.5
MEDIUMCVSS 3.1
EPSS 3.18%
Description
An authentication bypass flaw was found in the way krb5's certauth interface before 1.16.1 handled the validation of client certificates. A remote attacker able to communicate with the KDC could potentially use this flaw to impersonate arbitrary principals under rare and erroneous circumstances.
Affected products
-
- Version 1.16.1StatusaffectedConstraints-
- Version
Configuration 1
- 7.0
- 7.0
- 7.0
- 7.0
Configuration 2
- ≥ 1.0 · < 1.16.1
No data.
Red Hat Enterprise Linux 7
krb5-0:1.15.1-18.el7
Fixed · RHSA-2018:0666
Red Hat Enterprise Linux 5
krb5
Not affected
Red Hat Enterprise Linux 6
krb5
Not affected
Red Hat JBoss Core Services
krb5
Not affected
Red Hat JBoss Enterprise Application Platform 6
krb5
Not affected
Red Hat JBoss Enterprise Web Server 2
krb5
Not affected
| Product | Package | State | Advisory |
|---|---|---|---|
| Red Hat Enterprise Linux 7 | krb5-0:1.15.1-18.el7 | Fixed | RHSA-2018:0666 |
| Red Hat Enterprise Linux 5 | krb5 | Not affected | n/a |
| Red Hat Enterprise Linux 6 | krb5 | Not affected | n/a |
| Red Hat JBoss Core Services | krb5 | Not affected | n/a |
| Red Hat JBoss Enterprise Application Platform 6 | krb5 | Not affected | n/a |
| Red Hat JBoss Enterprise Web Server 2 | krb5 | Not affected | n/a |
No package ranges for this CVE.
Remediation
No remediation recorded yet.
Metrics
No CVSS v4.0 score for this CVE.
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N
CVSS:3.0/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N
AV:N/AC:L/Au:S/C:N/I:P/A:N
This CVE is not in the KEV list.
No CISA SSVC assessment for this CVE yet.
Estimated probability of exploitation in the wild in the next 30 days (FIRST EPSS). As of Oct 1, 2026.
Score over time
2021–2026- EPSS v1
- EPSS v2
- EPSS v3
- EPSS v4
- EPSS v5
Percentile over time
- EPSS v1
- EPSS v2
- EPSS v3
- EPSS v4
- EPSS v5
Table of values (20 key points)
Flat stretches are collapsed; showing up to 120 newest points.
| Date | Score | Percentile | Model |
|---|---|---|---|
| Oct 1, 2026 | 3.18% (0.03178) | 87.60th | v5 (v2026.06.15) |
| Jun 15, 2026 | 3.30% (0.03303) | 86.89th | v5 (v2026.06.15) |
| Mar 17, 2025 | 0.27% (0.00271) | 48.53th | v4 (v2025.03.14) |
| Dec 12, 2024 | 0.21% (0.00206) | 59.47th | v3 (v2023.03.01) |
| Mar 14, 2024 | 0.21% (0.00206) | 57.91th | v3 (v2023.03.01) |
| Feb 8, 2024 | 0.29% (0.00292) | 68.28th | v3 (v2023.03.01) |
| Dec 17, 2023 | 0.29% (0.00292) | 65.79th | v3 (v2023.03.01) |
| Jul 20, 2023 | 0.35% (0.00351) | 68.14th | v3 (v2023.03.01) |
| May 8, 2023 | 0.31% (0.00311) | 65.50th | v3 (v2023.03.01) |
| Mar 7, 2023 | 0.24% (0.00245) | 60.63th | v3 (v2023.03.01) |
| Mar 6, 2023 | 1.23% (0.01232) | 67.28th | v2 (v2022.01.01) |
| Feb 13, 2023 | 1.23% (0.01232) | 66.80th | v2 (v2022.01.01) |
| Feb 3, 2023 | 1.65% (0.01649) | 75.40th | v2 (v2022.01.01) |
| Dec 23, 2022 | 1.23% (0.01232) | 66.86th | v2 (v2022.01.01) |
| Apr 1, 2022 | 1.23% (0.01232) | 64.85th | v2 (v2022.01.01) |
| Feb 4, 2022 | 1.23% (0.01232) | 41.02th | v2 (v2022.01.01) |
| Feb 3, 2022 | 2.08% (0.02080) | 50.39th | v1 |
| Jan 6, 2022 | 2.08% (0.02080) | 49.89th | v1 |
| Sep 1, 2021 | 2.08% (0.02080) | 77.32th | v1 |
| Apr 14, 2021 | 2.08% (0.02080) | 0.00th | v1 |
References (11)
- http://www.securityfocus.com/bid/100511 vdb-entryx_refsource_BIDThird Party AdvisoryVDB Entry
- https://access.redhat.com/errata/RHSA-2018:0666 vendor-advisoryx_refsource_REDHATThird Party Advisory
- https://access.redhat.com/security/cve/CVE-2017-7562 Vendor Advisory
- https://bugzilla.redhat.com/show_bug.cgi?id=1485510 Issue Tracking
- https://bugzilla.redhat.com/show_bug.cgi?id=CVE-2017-7562 x_refsource_CONFIRMIssue TrackingPatchThird Party Advisory
- https://github.com/krb5/krb5/pull/694 x_refsource_CONFIRMPatchThird Party Advisory
- https://github.com/krb5/krb5/pull/694/commits/1de6ca2f2eb1fdbab51f1549a25a6903aefcc196 x_refsource_CONFIRMThird Party Advisory
- https://github.com/krb5/krb5/pull/694/commits/50fe4074f188c2d4da0c421e96553acea8378db2 x_refsource_CONFIRMThird Party Advisory
- https://github.com/krb5/krb5/pull/694/commits/b7af544e50a4d8291524f590e20dd44430bf627d x_refsource_CONFIRMThird Party Advisory
- https://nvd.nist.gov/vuln/detail/CVE-2017-7562
- https://www.cve.org/CVERecord?id=CVE-2017-7562
Change history (0)
No recorded changes yet.