Keycloak: Insufficient verification proof scoping enables identity provider account linking attack and account compromise
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.
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describes (1)
Related CVEs.
| ID | severity | exploitable | ||
|---|---|---|---|---|
| CVE-2026-9087US | high8.1 | — | ||
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, s… | ||||
02
references
External citations — patches, advisories, analysis.
- https://access.redhat.com/errata/RHSA-2026:25097WEB
- https://access.redhat.com/errata/RHSA-2026:25098WEB
- https://access.redhat.com/errata/RHSA-2026:30049WEB
- https://access.redhat.com/errata/RHSA-2026:30050WEB
- https://access.redhat.com/security/cve/CVE-2026-9087WEB
- https://bugzilla.redhat.com/show_bug.cgi?id=2480172WEB
- https://github.com/keycloak/keycloakPACKAGE
- https://github.com/keycloak/keycloak/commit/37dabf59d0b5ca3e5b3b272bcd3b2580e67b94ddWEB
scry
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