CVE-2026-15571: Red Hat Build Of Keycloak 26.6

High severity, CVSS 7.3. EPSS: 0.4% chance of exploitation in the next 30 days.

A flaw was found in the legacy client-initiated account-linking endpoint of Keycloak, a widely used open-source identity and access management solution. The mechanism used to protect the account-linking process from unauthorized requests relies on a hash that can be predicted by a malicious OIDC client. By tricking a user into authenticating, an attacker-controlled client can forge a valid linking URL to connect the victim's account to an attacker's external identity. This results in a full account takeover, allowing the attacker to log in as the victim.

Affected products

• Red Hat Red Hat Build Of Keycloak 26.6: before 26.6.6-1 (fixed in 26.6.6-1); before 26.6-12 (fixed in 26.6-12)
• Red Hat Red Hat Build Of Keycloak 26.6.6
• Red Hat Red Hat Data Grid 8
• Red Hat Red Hat JBoss Enterprise Application Platform Expansion Pack
• Red Hat Red Hat Single Sign-On 7

Published 2026-08-18. Last modified 2026-08-20.