CVE-2026-105305: Auth Bypass (CVSS 5.4)

Description

A flaw was found in the OIDC implementation of Keycloak, specifically within the Device Authorization Grant flow. This component allows devices with limited input capabilities to obtain security tokens. The issue occurs because the flow fails to check the minimum authentication level required by a client configuration. This allows an attacker who has stolen a user's password to bypass mandatory multi-factor authentication and gain unauthorized access to the Keycloak Admin REST API.

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CVSS v3.1 Score

5.4

MEDIUM

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

EPSS — Exploit Prediction

0.0019

Probability of exploitation

0.08%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-287 Improper Authentication

References

Other References

https://access.redhat.com/security/cve/CVE-2026-105305 https://bugzilla.redhat.com/show_bug.cgi?id=2545801

Frequently Asked Questions

What is CVE-2026-105305? +

A flaw was found in the OIDC implementation of Keycloak, specifically within the Device Authorization Grant flow. This component allows devices with limited input capabilities to obtain security tokens. The issue occurs because the flow fails to check the minimum authentication level required by a client configuration. This allows an attacker who has stolen a user's password to bypass mandatory multi-factor authentication and gain unauthorized access to the Keycloak Admin REST API. It has a CVSS v3.1 base score of 5.4 (MEDIUM).

How severe is CVE-2026-105305? +

CVE-2026-105305 has a CVSS v3.1 score of 5.4 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance. The EPSS score is 0.0019, placing it in the 0th percentile for exploitation probability.

How do I check if I'm vulnerable to CVE-2026-105305? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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CVE-2026-105305