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Fencer Vulns
medium 6.5

CVE-2023-1664 json

Keycloak Untrusted Certificate Validation vulnerability

published 2023-05-26 3 y ago modified 2026-06-17 4 mo ago also GHSA-5cc8-pgp5-7mpm , EUVD-2023-1697

cvss
6.5
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.4%
EPSS 0.4% chance of exploitation in 30 days, percentile 37%
public exploits
0
none known

Summary

A flaw was found in Keycloak. This flaw depends on a non-default configuration "Revalidate Client Certificate" to be enabled and the reverse proxy is not validating the certificate before Keycloak. Using this method an attacker may choose the certificate which will be validated by the server. If this happens and the KC_SPI_TRUSTSTORE_FILE_FILE variable is missing/misconfigured, any trustfile may be accepted with the logging information of "Cannot validate client certificate trust: Truststore not available". This may not impact availability as the attacker would have no access to the server, but consumer applications Integrity or Confidentiality may be impacted considering a possible access to them. Considering the environment is correctly set to use "Revalidate Client Certificate" this flaw is avoidable.

Patch / fix

  • maven org.keycloak:keycloak-core 21.1.2
  • rh-sso7-keycloak red hat single sign on 7.6 18.0.8-1.redhat_00001.1.el9sso
  • rh-sso7-keycloak-server red hat single sign on 7.6 18.0.8-1.redhat_00001.1.el9sso
  • rh-sso7-keycloak red hat single sign on 7.6 18.0.8-1.redhat_00001.1.el8sso
  • rh-sso7-keycloak-server red hat single sign on 7.6 18.0.8-1.redhat_00001.1.el8sso
  • rh-sso7-keycloak red hat single sign on 7.6 18.0.8-1.redhat_00001.1.el7sso
  • rh-sso7-keycloak-server red hat single sign on 7.6 18.0.8-1.redhat_00001.1.el7sso

red hat advisories RHSA-2023:3885RHSA-2023:3884RHSA-2023:3883

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-2023-1664 updated cvss 6.5

keycloak: Untrusted Certificate Validation

  • Red Hat Migration Toolkit for Runtimes org.keycloak-keycloak-core
    affected: workaround, no fix available
  • Red Hat build of Apicurio Registry 2 keycloak-core Red Hat build of Quarkus keycloak-core Red Hat Fuse 7 keycloak-core
    affected: workaround, no fix available “Fix deferred”
  • Red Hat AMQ Broker 7.11.2
    fixed: vendor fix RHSA-2023:5491
  • Red Hat Middleware Containers for OpenShift rh-sso-7/sso76-openshift-rhel8 7.6-24
    fixed: vendor fix RHSA-2023:3888
  • Red Hat Single Sign-On 7
    fixed: vendor fix RHSA-2023:3892
  • Red Hat Single Sign-On 7.6 for RHEL 7 Server rh-sso7-keycloak 18.0.8-1.redhat_00001.1.el7sso, rh-sso7-keycloak-server 18.0.8-1.redhat_00001.1.el7sso
    fixed: vendor fix RHSA-2023:3883
  • Red Hat Single Sign-On 7.6 for RHEL 8 rh-sso7-keycloak 18.0.8-1.redhat_00001.1.el8sso, rh-sso7-keycloak-server 18.0.8-1.redhat_00001.1.el8sso
    fixed: vendor fix RHSA-2023:3884
  • Red Hat Single Sign-On 7.6 for RHEL 9 rh-sso7-keycloak 18.0.8-1.redhat_00001.1.el9sso, rh-sso7-keycloak-server 18.0.8-1.redhat_00001.1.el9sso
    fixed: vendor fix RHSA-2023:3885
show 1 more
  • Red Hat Satellite 6 keycloak-httpd-client-install, python2-keycloak-httpd-client-install
    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

CISA SSVC

Exploitation
none
Automatable
yes
Technical impact
partial
Assessed
21 mo ago

Exploit prediction

0.43% chance of exploitation in the next 30 days, higher than 37% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CISA ADP 3.1 6.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N
NVD 3.1 6.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N
CNA 3.1 6.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N
GitHub 3.1 6.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N

Affected packages

ecosystem package affected fixed in
maven org.keycloak:keycloak-core
<21.1.2
21.1.2

Affected products

  • n/a Keycloak

Classification

Weakness
  • CWE-295 Improper Certificate Validation

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.