SB2026051194 - Open redirect in authlib

Description

This security bulletin contains information about 1 vulnerability.

1) Open redirect (CVE-ID: CVE-2026-44681)

CWE-ID: CWE-601 - URL Redirection to Untrusted Site ('Open Redirect')

CVSSv4: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:N/VI:L/VA:N/SC:L/SI:L/SA:N/E:U/U:Green

The vulnerability allows a remote attacker to redirect users to an attacker-controlled URL.

The vulnerability exists due to url redirection to an untrusted site in OpenIDImplicitGrant and OpenIDHybridGrant authorization request validation when processing authorization requests that omit the openid scope. A remote attacker can send a specially crafted authorization request with an attacker-controlled redirect_uri to redirect users to an attacker-controlled URL.

Exploitation requires an authorization server deployment that registers the OIDC Implicit or Hybrid grant types, and user interaction is required.

Remediation

Install update from vendor's website.

References

• https://github.com/authlib/authlib/security/advisories/GHSA-r95x-qfjj-fjj2
• https://github.com/authlib/authlib/commit/3be08468