CVE-2026-15571

Received Received - Intake

Account Takeover via Predictable Account-Linking Hash in Keycloak

Publication date: 2026-08-18

Last updated on: 2026-08-18

Assigner: redhat-SADP

Description

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.

CVSS Scores

EPSS Scores

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Meta Information

Published

2026-08-18

Last Modified

2026-08-18

Generated

2026-08-19

AI Q&A

2026-08-19

EPSS Evaluated

N/A

NVD

CVE-2026-15571

EUVD

EUVD-2026-61238

Affected Vendors & Products

Vendor	Product	Version / Range
keycloak	keycloak	*

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
CWE-341	A number or object is predictable based on observations that the attacker can make about the state of the system or network, such as time, process ID, etc.

Attack-Flow Graph

Executive Summary

This vulnerability is in Keycloak's legacy client-initiated account-linking endpoint. It allows an attacker to predict a hash used for security, forge a valid linking URL, and trick a user into authenticating. This connects the victim's account to the attacker's external identity, enabling full account takeover.

Impact Analysis

If exploited, an attacker could gain full access to your Keycloak account. This could lead to unauthorized actions, data theft, or impersonation. Users should avoid clicking suspicious links and update Keycloak to the latest version.

Mitigation Strategies

Update Keycloak to the latest patched version immediately to address the flawed account-linking endpoint. Review and restrict access to OIDC clients, especially those with account-linking privileges. Monitor authentication logs for suspicious activity or unauthorized account linkages.

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