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Fencer Vulns
medium 6.5

CVE-2017-7562 json

An authentication bypass flaw was found in the way krb5's certauth interface before 1.16.1 handled the validation of client certificates.

published 2018-07-26 8 y ago modified 2026-06-17 4 mo ago also EUVD-2017-16567

cvss
6.5
version 3.0, CNA
cisa kev
Not listed
not in CISA's catalog
epss
3.2%
EPSS 3.2% chance of exploitation in 30 days, percentile 88%
public exploits
0
none known

Summary

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.

Patch / fix

  • mit kerberos_5 1.16.1
  • krb5 RHEL 7 1.15.1-18.el7
  • libkadm5 RHEL 7 1.15.1-18.el7
  • krb5-libs RHEL 7 1.15.1-18.el7
  • krb5-pkinit RHEL 7 1.15.1-18.el7
  • krb5-server RHEL 7 1.15.1-18.el7
  • krb5-server-ldap RHEL 7 1.15.1-18.el7
  • krb5-workstation RHEL 7 1.15.1-18.el7

red hat advisories RHSA-2018:0666

  • krb5 SLES for SAP 12 SP1, SLES 12-LTSS, SLES 12 SP1-LTSS 1.12.1-38.5.3

suse advisories SUSE-SU-2018:1425-1

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2017-7562 updated cvss 6.5

krb5: Authentication bypass by improper validation of certificate EKU and SAN

  • Red Hat Enterprise Linux Client (v. 7) krb5 1.15.1-18.el7, libkadm5 1.15.1-18.el7, krb5-libs 1.15.1-18.el7, krb5-pkinit 1.15.1-18.el7, krb5-workstation 1.15.1-18.el7 Red Hat Enterprise Linux Client Optional (v. 7) krb5-server 1.15.1-18.el7, krb5-server-ldap 1.15.1-18.el7 Red Hat Enterprise Linux ComputeNode (v. 7) krb5 1.15.1-18.el7, libkadm5 1.15.1-18.el7, krb5-libs 1.15.1-18.el7, krb5-pkinit 1.15.1-18.el7, krb5-workstation 1.15.1-18.el7 Red Hat Enterprise Linux ComputeNode Optional (v. 7) krb5-server 1.15.1-18.el7, krb5-server-ldap 1.15.1-18.el7 Red Hat Enterprise Linux for ARM and IBM Power LE (POWER9) Server (v. 7) krb5 1.15.1-18.el7, libkadm5 1.15.1-18.el7, krb5-libs 1.15.1-18.el7, krb5-pkinit 1.15.1-18.el7, krb5-server 1.15.1-18.el7, krb5-server-ldap 1.15.1-18.el7, +1 more Red Hat Enterprise Linux Server (v. 7) krb5 1.15.1-18.el7, libkadm5 1.15.1-18.el7, krb5-libs 1.15.1-18.el7, krb5-pkinit 1.15.1-18.el7, krb5-server 1.15.1-18.el7, krb5-server-ldap 1.15.1-18.el7, +1 more
    +1 more products
    Red Hat Enterprise Linux Workstation (v. 7) krb5 1.15.1-18.el7, libkadm5 1.15.1-18.el7, krb5-libs 1.15.1-18.el7, krb5-pkinit 1.15.1-18.el7, krb5-server 1.15.1-18.el7, krb5-server-ldap 1.15.1-18.el7, +1 more
    fixed: vendor fix RHSA-2018:0666
  • Red Hat Enterprise Linux 5 krb5 Red Hat Enterprise Linux 6 krb5, libkadm5, krb5-libs, krb5-server, krb5-server-ldap, krb5-workstation, +1 more Red Hat JBoss Core Services krb5 Red Hat JBoss Enterprise Application Platform 6 krb5 Red Hat JBoss Enterprise Web Server 2 krb5
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

Exploit prediction

3.18% chance of exploitation in the next 30 days, higher than 88% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.0 6.5 CVSS:3.0/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N
NVD 3.1 6.5 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N
NVD 2.0 4.0 AV:N/AC:L/Au:S/C:N/I:P/A:N

Affected products

  • MIT krb5

Classification

Weakness
  • CWE-295 Improper Certificate Validation
  • CWE-287 Improper Authentication

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.