GHSA-m6qj-3mpp-57v8

Keycloak: Insufficient verification proof scoping enables identity provider account linking attack and account compromise

At a glance

Published: 2026-05-20 18:31 UTC
Updated: 2026-06-26 12:21 UTC
CVE: CVE-2026-9087
CVSS_V3: CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:U/C:H/I:H/A:N

Description

A flaw was found in Keycloak. The cross-session verification proof is keyed only by (local userId, idpAlias) and is not bound to the upstream identity that was actually verified, so a second upstream account on the same IdP can consume it and get linked to the victim's local account.

Affected packages

Package	Versions
Maven · org.keycloak:keycloak-services	introduced 0, fixed 26.6.3

References

https://nvd.nist.gov/vuln/detail/CVE-2026-9087 ADVISORY
https://github.com/keycloak/keycloak/commit/37dabf59d0b5ca3e5b3b272bcd3b2580e67b94dd WEB
https://access.redhat.com/errata/RHSA-2026:25097 WEB
https://access.redhat.com/errata/RHSA-2026:25098 WEB
https://access.redhat.com/errata/RHSA-2026:30049 WEB
https://access.redhat.com/errata/RHSA-2026:30050 WEB
https://access.redhat.com/security/cve/CVE-2026-9087 WEB
https://bugzilla.redhat.com/show_bug.cgi?id=2480172 WEB
https://github.com/keycloak/keycloak PACKAGE
https://github.com/keycloak/keycloak/releases/tag/26.6.3 WEB

Sources

Source	Licence
OSV.dev	CC-BY 4.0 — GitHub Advisory Database