CVE-2026-18209

low

Published 2026-07-31 · Modified 2026-07-31

Discuss on Community Propose mitigation

CVSS v3

3.4

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

CVSS v4 NEW

—

not yet in upstream

VIR risk

3.4

Description

A flaw was found in the keycloak-services component of Keycloak, which handles OpenID Connect (OIDC) authentication flows. The issue occurs because the security check designed to prevent HTTP parameter pollution only inspects the query portion of a redirect URL and ignores the fragment portion. When a client is configured with a wildcard redirect URI, an attacker can use this to inject duplicate security parameters into the login response. If a client application is not configured correctly, it might trust the attacker's injected data instead of the real security information from Keycloak, leading to session fixation or account confusion.

Predictions

Exploit likelihood

45%

Patch ETA

—

Heuristic predictions, AS-IS, for prioritization only.

Mitigations

No mitigations published for this CVE yet.

The vendor-content worker queues fetches as references arrive (check back in a few minutes). Or — if you've already worked around this in production — publish your fix to the community-verified tier.

Propose a mitigation on Community Mitigations published via the community go through AI scoring + 2 human reviewers + 7-day silent objection window before landing here with source_tier=community-verified.

References

CWEs

CWE-1288

Community-verified mitigations for this CVE will appear above when contributors publish them.

Verify integrity in audit chain (admin only). AS-IS.