CVE-2026-18203
mediumpriority · track · 0OT risk · elevatedEPSS 0.003 · 24 %ileDEEUUSEPSS · scored 2026-10-27
A flaw was found in the group policy evaluation logic of Keycloak, an identity and access management solution. When a group policy is set to extend permissions to child groups, the system incorrectly uses a simple text-based prefix check to verify group membership. This allows a user who belongs to a different group with a similar starting name to bypass security checks and gain unauthorized access to administrative functions or protected resources.
cvss
Technical severity, 0–10. One row per scoring source.
base score 0–10 · higher = more severe · hover a vector to decode
ssvc
A stakeholder decision — act, attend, or track — from exploitation and impact.
weaknesses
The CWE weakness classes this flaw belongs to.
affected products (2)
Products and version ranges known to be affected.
advisories (1)
Vendor and ecosystem advisories describing this.
- WID-SEC-W-2026-2614Keycloak: Mehrere SchwachstellenDeutsch2026-08-02csaf · cert_bundDE
Ein Angreifer kann mehrere Schwachstellen in Keycloak ausnutzen, um seine Privilegien zu erhöhen, Sicherheitsmaßnahmen zu umgehen, Daten zu manipulieren und sensible Informationen offenzulegen.
also known as (3)
Other names and identifiers for this entity.
sources
Which sources assert this record, and when.
references (6)
External citations — patches, advisories, analysis.
- https://access.redhat.com/security/cve/CVE-2026-18203cnnvd
- https://bugzilla.redhat.com/show_bug.cgi?id=2508291cnnvd
- https://access.redhat.com/security/cve/CVE-2026-18203enisa_euvd
- https://bugzilla.redhat.com/show_bug.cgi?id=2508291enisa_euvd
- https://access.redhat.com/security/cve/CVE-2026-18203Vendor Advisorynvd
- https://bugzilla.redhat.com/show_bug.cgi?id=2508291Issue TrackingVendor Advisorynvd
Attackers weaponise vulnerabilities like this against internet-exposed services. See what is exposed on your perimeter with a free passive scan.
Free scan