Org.keycloak/keycloak-quarkus-server: keycloak: proxy bypass due to improper handling of matrix parameters in url paths

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-0976
StatePUBLISHED
Assignerredhat
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-01-15 13:16:04 UTC
Updated2026-08-09 19:17:00 UTC
DescriptionA flaw was found in Keycloak. This improper input validation vulnerability occurs because Keycloak accepts RFC-compliant matrix parameters in URL path segments, while common reverse proxy configurations may ignore or mishandle them. A remote attacker can craft requests to mask path segments, potentially bypassing proxy-level path filtering. This could expose administrative or sensitive endpoints that operators believe are not externally reachable.

Risk And Classification

Primary CVSS: v3.1 3.7 LOW from [email protected]

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

EPSS: 0.003540000 probability, percentile 0.281220000 (date 2026-08-09)

Problem Types: CWE-20 | CWE-20 Improper Input Validation

VersionSourceTypeScoreSeverityVector
3.1[email protected]Secondary3.7LOWCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N
3.1CNACVSS3.7LOWCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N

CVSS v3.1 Breakdown

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

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

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Red Hat Red Hat Build Of Keycloak Not specified Not specified
CNA Red Hat Red Hat JBoss Enterprise Application Platform 8 Not specified Not specified
CNA Red Hat Red Hat JBoss Enterprise Application Platform 8 Not specified Not specified
CNA Red Hat Red Hat JBoss Enterprise Application Platform 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 JBoss Enterprise Application Platform Expansion Pack Not specified Not specified
CNA Red Hat Red Hat JBoss Enterprise Application Platform Expansion Pack Not specified Not specified

References

ReferenceSourceLinkTags
bugzilla.redhat.com/show_bug.cgi [email protected] bugzilla.redhat.com
access.redhat.com/security/cve/CVE-2026-0976 [email protected] access.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 Alexander Schwartz (RedHat) for reporting this issue. (en)

Additional Advisory Data

SourceTimeEvent
CNA2026-01-15T06:43:23.112ZReported to Red Hat.
CNA2026-01-15T00:00:00.000ZMade public.

Workarounds

CNA: To mitigate this issue, ensure that all administrative and sensitive endpoints within Keycloak are adequately protected by robust authentication and authorization policies, independent of any reverse proxy path filtering. Operators should review Keycloak's internal access controls to confirm that access to these endpoints is restricted to authorized users and roles.

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