Keycloak-services: keycloak-services: required signed-jwt assertion policy can be bypassed with unsigned assertion headers

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-16093
StatePUBLISHED
Assignerredhat
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-07-17 17:17:14 UTC
Updated2026-07-21 03:16:40 UTC
DescriptionKeycloak provides a mechanism called Client Policies to enforce security requirements on clients, such as requiring them to use signed JWTs for authentication. A flaw was discovered where this enforcement can be bypassed. An attacker with valid client credentials can provide a fake, unsigned assertion header that tricks the system into thinking the policy requirements have been met. This allows the attacker to authenticate using simpler methods like a client secret even when the administrator has mandated more secure, signed assertions.

Risk And Classification

Primary CVSS: v3.1 5.4 MEDIUM from [email protected]

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

EPSS: 0.001930000 probability, percentile 0.092350000 (date 2026-07-21)

Problem Types: CWE-807 | CWE-807 Reliance on Untrusted Inputs in a Security Decision

VersionSourceTypeScoreSeverityVector
3.1[email protected]Secondary5.4MEDIUMCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N
3.1CNACVSS5.4MEDIUMCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
Low
Integrity
Low
Availability
None

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

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Red Hat Red Hat Build Of Keycloak Not specified Not specified
CNA Red Hat Red Hat Build Of Keycloak Not specified Not specified
CNA Red Hat Red Hat Build Of Keycloak Not specified Not specified
CNA Red Hat Red Hat Data Grid 8 Not specified Not specified
CNA Red Hat Red Hat JBoss Enterprise Application Platform Expansion Pack Not specified Not specified
CNA Red Hat Red Hat Single Sign-On 7 Not specified Not specified

References

ReferenceSourceLinkTags
access.redhat.com/security/cve/CVE-2026-16093 [email protected] access.redhat.com
bugzilla.redhat.com/show_bug.cgi [email protected] bugzilla.redhat.com
CVE Program record CVE.ORG www.cve.org canonical
NVD vulnerability detail NVD nvd.nist.gov canonical, analysis

Vendor Comments And Credit

Discovery Credit

CNA: Red Hat would like to thank Paul Bottinelli (Trail of Bits) for reporting this issue. (en)

Additional Advisory Data

SourceTimeEvent
CNA2026-07-16T17:01:13.000ZReported to Red Hat.
CNA2026-07-16T17:01:13.000ZMade public.

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