# CVE-2026-16093: Red Hat Keycloak Client Policy bypass in keycloak-services

Source: https://junglewise.ai/threats/cve-2026-16093-red-hat-keycloak-client-policy-bypass-in-keycloak-services  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-07-17. Updated: 2026-07-17  
License: CC BY 4.0 with a link back

CVE-2026-16093 · Severity: medium · CVSS 5.4 · Published 2026-07-17

Keycloak, a popular identity and access management solution, contains a flaw in its security policy enforcement. Administrators can set policies requiring clients to use secure, signed digital signatures (JWTs) for authentication; however, this protection can be bypassed. An attacker with basic client credentials can use a fake, unsigned header to trick the system into accepting less secure authentication methods, potentially undermining the organization's security standards for application access.

Technologies: [Red Hat build of Keycloak](https://junglewise.ai/threats/technologies/red-hat-keycloak), [Red Hat Data Grid 8](https://junglewise.ai/threats/technologies/data-grid-8), [Red Hat Single Sign-On 7](https://junglewise.ai/threats/technologies/single-sign-on-7). Vendors: [Red Hat](https://junglewise.ai/threats/vendors/red-hat).

## Quick answers

**Is CVE-2026-16093 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-16093 being exploited in the wild.

**How severe is CVE-2026-16093?** Medium severity, with a CVSS score of 5.4, published 17 July 2026.

**Which products and versions are affected?** Red Hat Build of Keycloak; Red Hat Single Sign-On 7; Red Hat Data Grid 8; Red Hat JBoss Enterprise Application Platform Expansion Pack.

**Is there a fix for CVE-2026-16093?** No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

**How is CVE-2026-16093 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-16093?** Check whether you run Red Hat build of Keycloak, Red Hat Data Grid 8 or Red Hat Single Sign-On 7. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

A vulnerability in the Secure Client Registration executor within the keycloak-services component allows for a bypass of the signed-JWT assertion policy. The root cause is located in the SecureSigningAlgorithmForSignedJwtExecutor, which incorrectly validates only the 'alg' field in the raw JWT header without verifying the presence of a valid client assertion type or ensuring the client's authenticator is assertion-based. By submitting a crafted request with an unsigned assertion header containing a valid 'alg' field, an authenticated attacker can bypass signature verification. This enables the use of simpler authentication methods (like client secrets) even when administrative policies mandate signed assertions.

## Affected products

- Red Hat Build of Keycloak
- Red Hat Single Sign-On 7
- Red Hat Data Grid 8
- Red Hat JBoss Enterprise Application Platform Expansion Pack

## Timeline

- 2026-07-17: disclosed
- 2026-07-17: advisory

## References

- [https://access.redhat.com/downloads/content/package-browser/](https://access.redhat.com/downloads/content/package-browser/)
- [https://access.redhat.com/jbossnetwork/restricted/listSoftware.html](https://access.redhat.com/jbossnetwork/restricted/listSoftware.html)
- [https://access.redhat.com/security/cve/CVE-2026-16093](https://access.redhat.com/security/cve/CVE-2026-16093)
- [https://bugzilla.redhat.com/show_bug.cgi?id=2501729](https://bugzilla.redhat.com/show_bug.cgi?id=2501729)

## Related threats

- [Keycloak server arbitrary code execution in client authorization](https://junglewise.ai/threats/cve-2026-120984-a-flaw-was-found-in-the-keycloak-server-s-client-management)
- [Red Hat Build of Keycloak OIDC logout session fixation](https://junglewise.ai/threats/cve-2026-107124-a-flaw-was-found-in-the-oidc-logout-endpoint-of-the-keycloak)
- [Keycloak theme resource disk exhaustion](https://junglewise.ai/threats/cve-2026-110932-a-flaw-was-found-in-the-theme-resource-endpoint-of-keycloak-an)
- [Keycloak secure-redirect-uris-enforcer open redirect via DNS resolution](https://junglewise.ai/threats/cve-2026-118425-a-flaw-was-found-in-the-secure-redirect-uris-enforcer-client)
- [Keycloak OIDC Dynamic Client Registration offline token revocation bypass](https://junglewise.ai/threats/cve-2026-107623-a-flaw-was-found-in-the-oidc-dynamic-client-registration-dcr)