CVE-2023-1664 — keycloak-core
MEDIUMCVE-2023-1664 is a medium-severity (CVSS 6.5) CWE-295 vulnerability in org.keycloak:keycloak-core. A fix is available for org.keycloak:keycloak-core — see the affected versions and patch details below.
Keycloak Untrusted Certificate Validation vulnerability
Exploitation Status
No confirmed exploitation observed yet
- CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for CVE-2023-1664.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
Where this sits among everything scored
Real-World Exposure
org.keycloak:keycloak-coreReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects Maven packages — download data is not available via public APIs for these ecosystems.
Description
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.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| ☕Maven | org.keycloak:keycloak-core | all versions | 21.1.2org.keycloak:keycloak-core:21.1.2 |
Affected Products
build of quarkusredhatjboss a-mqredhatkeycloakredhatmigration toolkit for runtimesredhatsingle sign-onredhatDetection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for org.keycloak:keycloak-core, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update org.keycloak:keycloak-core to 21.1.2 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2023-1664 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
Fixing This On Your OS
If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.
Red Hat Impact rated as a low impact considering there's a mitigation for this issue which would be consider the environment is correctly set with the truststore file. With these settings, the environment there's no evidence of attack possibility. Also it's possible to track under the server logs for more evidences.
Make sure KC_SPI_TRUSTSTORE_FILE_FILE is correctly set and the logs are not reporting the "Cannot validate client certificate trust: Truststore not available" after an attempt to explore the vulnerability. Note this message may happen under other scenarios and reasons but the expected behavior would be that a non-valid certificate to pass.Source: Red Hat security advisory for CVE-2023-1664 (CC BY 4.0)
| Product | Fixed in | Advisory |
|---|---|---|
| AMQ Broker 7.11.2 | keycloak-core | RHSA-2023:5491 |
| Red Hat Single Sign-On 7 | rh-sso7-keycloak | RHSA-2023:3892 |
| Red Hat Single Sign-On 7.6 for RHEL 7 | rh-sso7-keycloak-0:18.0.8-1.redhat_00001.1.el7sso | RHSA-2023:3883 |
| Red Hat Single Sign-On 7.6 for RHEL 8 | rh-sso7-keycloak-0:18.0.8-1.redhat_00001.1.el8sso | RHSA-2023:3884 |
| Red Hat Single Sign-On 7.6 for RHEL 9 | rh-sso7-keycloak-0:18.0.8-1.redhat_00001.1.el9sso | RHSA-2023:3885 |
| RHEL-8 based Middleware Containers | rh-sso-7/sso76-openshift-rhel8:7.6-24 | RHSA-2023:3888 |
Frequently Asked Questions
Is CVE-2023-1664 in your dependencies?
Find it across Maven, including transitive dependencies.