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CVE-2023-1664

Keycloak Untrusted Certificate Validation vulnerability

6.5 MediumFix available

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.

Attack profile

How easy it is to exploit

Attack vector
Network
Complexity
Low
Privileges needed
None
User interaction
None

What an attacker can affect

Confidentiality
Low
Integrity
Low
Availability
None

Exploit likelihood

0.43%Up 0.4 points since May 27, 2023
90%50%10%1%

What each source reports

NVD Score used 6.5

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.

Record
CVE-2023-1664
CVSS 3.1
6.5 MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N
Weakness
CWE-295
Updated
2026-11-02
CVE List 6.5

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.

Record
CVE-2023-1664
CVSS 3.1
6.5 MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N
Weakness
CWE-295
Updated
2026-11-02
EUVDEUVD-2023-1697 6.5

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.

Record
EUVD-2023-1697
CVSS 3.1
6.5 MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N
Updated
2026-11-03
GitHub AdvisoriesGHSA-5cc8-pgp5-7mpm 6.5

Keycloak Untrusted Certificate Validation vulnerability

A flaw was found in keycloak-core. This flaw considers the scenario when using X509 Client Certificate Authenticatior with the option "Revalidate Client Certificate". A user may be able to choose, if directly connect to keycloak (not passing via reverse proxy) a specific certificate. If there's a configuration error in KC_SPI_TRUSTSTORE_FILE_FILE the authenticator allows even with the "Cannot validate client certificate trust: Truststore not available" message as there's no certificate to trust against.

Record
GHSA-5cc8-pgp5-7mpm
CVSS 3.1
6.5 MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N
Weakness
CWE-295
Updated
2026-11-02
OSV 6.5

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.

Record
CVE-2023-1664
CVSS 3.1
6.5 MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N
Weakness
CWE-295
Updated
2026-11-02
OSVGHSA-5cc8-pgp5-7mpm 6.5

Keycloak Untrusted Certificate Validation vulnerability

A flaw was found in keycloak-core. This flaw considers the scenario when using X509 Client Certificate Authenticatior with the option "Revalidate Client Certificate". A user may be able to choose, if directly connect to keycloak (not passing via reverse proxy) a specific certificate. If there's a configuration error in KC_SPI_TRUSTSTORE_FILE_FILE the authenticator allows even with the "Cannot validate client certificate trust: Truststore not available" message as there's no certificate to trust against.

Record
GHSA-5cc8-pgp5-7mpm
CVSS 3.1
6.5 MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N
Weakness
CWE-295
Updated
2026-11-02
OSVRHSA-2023:3883 8.1

Red Hat Security Advisory: Red Hat Single Sign-On 7.6.4 security update on RHEL 7

Record
RHSA-2023:3883
CVSS 3.1
8.1 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N
Updated
2026-11-02
OSVRHSA-2023:3884 8.1

Red Hat Security Advisory: Red Hat Single Sign-On 7.6.4 security update on RHEL 8

Record
RHSA-2023:3884
CVSS 3.1
8.1 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N
Updated
2026-11-02
OSVRHSA-2023:3885 8.1

Red Hat Security Advisory: Red Hat Single Sign-On 7.6.4 security update on RHEL 9

Record
RHSA-2023:3885
CVSS 3.1
8.1 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N
Updated
2026-11-02

Affected products

Affected packages

Affected packages
PackageAffectedFixed
org.keycloak:keycloak-core
Maven
 before 21.1.2
21.1.2
org.keycloak:keycloak-core
Maven
 before 21.1.2, plus listed versions
1.0-alpha-11.0-alpha-1-120620131.0-alpha-21.0-alpha-31.0-alpha-4
Show 45 moreShow less
1.0-beta-11.0-beta-1-201505211.0-beta-1-201505231.0-beta-21.0-beta-31.0-beta-41.0-final1.0-rc-11.0-rc-21.0.1.Final1.0.2.Final1.0.3.Final1.0.4.Final1.0.5.Final1.1.0.Beta11.1.0.Beta21.1.0.Final1.1.1.Final1.2.0.Beta11.2.0.CR11.2.0.Final1.3.0.Final1.3.1.Final1.4.0.Final1.5.0-Final1.5.0.Final1.5.1.Final1.6.0.Final1.6.1.Final1.7.0.CR11.7.0.Final1.8.0.Alpha11.8.0.CR11.8.0.CR21.8.0.CR31.8.0.Final1.8.1.Final1.9.0.CR11.9.0.Final1.9.1.Final1.9.2.Final1.9.3.Final1.9.4.Final1.9.5.Final1.9.7.Final
21.1.2
rh-sso7-keycloak
Red Hat:red_hat_single_sign_on:7.6::el7
From an advisory covering 5 CVEs
 before 0:18.0.8-1.redhat_00001.1.el7sso
0:18.0.8-1.redhat_00001.1.el7sso
rh-sso7-keycloak-server
Red Hat:red_hat_single_sign_on:7.6::el7
From an advisory covering 5 CVEs
 before 0:18.0.8-1.redhat_00001.1.el7sso
0:18.0.8-1.redhat_00001.1.el7sso
rh-sso7-keycloak
Red Hat:red_hat_single_sign_on:7.6::el8
From an advisory covering 5 CVEs
 before 0:18.0.8-1.redhat_00001.1.el8sso
0:18.0.8-1.redhat_00001.1.el8sso
rh-sso7-keycloak-server
Red Hat:red_hat_single_sign_on:7.6::el8
From an advisory covering 5 CVEs
 before 0:18.0.8-1.redhat_00001.1.el8sso
0:18.0.8-1.redhat_00001.1.el8sso
rh-sso7-keycloak
Red Hat:red_hat_single_sign_on:7.6::el9
From an advisory covering 5 CVEs
 before 0:18.0.8-1.redhat_00001.1.el9sso
0:18.0.8-1.redhat_00001.1.el9sso
rh-sso7-keycloak-server
Red Hat:red_hat_single_sign_on:7.6::el9
From an advisory covering 5 CVEs
 before 0:18.0.8-1.redhat_00001.1.el9sso
0:18.0.8-1.redhat_00001.1.el9sso

History

History
RecordedChangedSources
affected, facts
aliases, productsEUVD
first indexedCVE List, GitHub Advisories, NVD, OSV

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2023-1664 is a medium vulnerability (CVSS 6.5) in Keycloak, published May 26, 2023. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.43%, the 37th percentile. Fixed in org.keycloak:keycloak-core 21.1.2.

References

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Left out here: 103 versions. The JSON record has them.

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