Keycloak Untrusted Certificate Validation vulnerability

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

6.5 · CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N

EPSS

• CVE-2023-1664: 0.43% estimated exploitation activity in the next 30 days; percentile 36.82 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

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 KCSPITRUSTSTOREFILEFILE the authenticator allows even with the "Cannot validate client certificate trust: Truststore not available" message as there's no certificate to trust against.

Published by the source

30 Jun 2023, 20:30 UTC

Last modified by the source

30 Jun 2023, 20:30 UTC

Source last checked

26 Oct 2026, 16:11 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-5cc8-pgp5-7mpm

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# Patch Next advisory brief: CVE-2023-1664

Advisory: Keycloak Untrusted Certificate Validation vulnerability
IDs: CVE-2023-1664, GHSA-5cc8-pgp5-7mpm
Record: https://patchnext.com/advisories/cve-2023-1664 (revision 1, source checked 26 Oct 2026, 16:11 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 6.5)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: org.keycloak:keycloak-core 21.1.2. A vendor fix does not mean a deployment is fixed.

## Affected components
- Maven org.keycloak:keycloak-core: affected < 21.1.2; fixed in 21.1.2

## Suggested inspection (read-only)
- Maven org.keycloak:keycloak-core: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on org.keycloak:keycloak-core.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-5cc8-pgp5-7mpm (GitHub-reviewed advisory GHSA-5cc8-pgp5-7mpm lists affected ranges: Maven org.keycloak:keycloak-core >=0 <21.1.2)

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