PYSEC-2026-4359

    Dashboard / Vulnerabilities / PYSEC-2026-4359

    PYSEC-2026-4359

    Published: 22 Oct 2026Last Modified: 30 Oct 2026

    Summary:

    Details: Authlib is a Python library which builds OAuth and OpenID Connect servers. Prior to 1.9.0, OpenIDImplicitGrant.validate_authorization_request() checks the client-controlled raw request.payload.scope for openid after the parent grant has filtered allowed scopes into request.scope. A registered client permitted an ID token response type but not the openid scope can add openid to the request, obtain user consent, and receive a signed ID token containing the user's subject and allowed profile claims. Authorization code flow and deployments that allow openid for every client permitted an ID token response are not affected. In authlib/oidc/core/grants/implicit.py, OpenIDImplicitGrant.validate_authorization_request() checks request.payload.scope instead of the filtered request.scope. This issue is fixed in version 1.9.0.

    References: https://github.com/authlib/authlib/releases/tag/v1.9.0, https://github.com/authlib/authlib/commit/e3bd41cb29dcfee434453b135ffb487884baeedf, https://github.com/authlib/authlib/pull/945, https://github.com/authlib/authlib/security/advisories/GHSA-q686-2qmg-hqc7

    Affected packages

    Package

    Name: authlib

    Purl: pkg:pypi/authlib

    Affected ranges

    Type: ECOSYSTEM

    Events:

    Introduced- 0
    Fixed -1.9.0

    Affected versions

    0.1

    Common Vulnerability Scoring System

    Attack Vector
    Network
    Adjacent
    Local
    Physical
    Privileges Required
    None
    Low
    High
    User Interaction
    None
    Required
    Scope
    Unchanged
    Changed
    Confidentiality
    None
    Low
    High
    Integrity
    None
    Low
    High
    Availability
    None
    Low
    High