CVE-2026-115910: Python Social Auth: OpenID Connect nonce is not bound to the browser session, so a stolen authorization code logs the attacker in as the victim

Vulnerability summary

CVE-2026-115910 is a medium (CVSS 6.8) vulnerability in python-social-auth social-core. EPSS estimates a 0.16% chance of exploitation in the next 30 days, higher than 4.8% of scored vulnerabilities.

Timeline

1. 26-10-2026
   PublishedVulnerability first disclosed.
2. 31-10-2026
   Last modifiedVulnerability information updated.

Description

Python Social Auth is a social authentication and registration mechanism. Prior to 6.2.0, OpenIdConnectAuth in social_core/backends/open_id_connect.py uses get_and_store_nonce to place the OpenID Connect nonce in a shared OpenIdConnectAssociation table, and get_nonce and validate_claims verify only that the nonce exists and has not expired rather than binding it to the browser session and OAuth state that initiated the login. An attacker who obtains a victim's unused authorization code can start a separate login to obtain valid state for the attacker's browser, submit the victim's code with that state, and pass nonce validation because the victim nonce is globally available. With DEFAULT_USE_PKCE disabled in the default OpenIdConnectAuth configuration, the attacker can be logged in as the victim. This issue is fixed in version 6.2.0.

• CWE-345Insufficient Verification of Data AuthenticityThe product does not sufficiently verify the origin or authenticity of data, in a way that causes it to accept invalid data.
• CWE-384Session FixationAuthenticating a user, or otherwise establishing a new user session, without invalidating any existing session identifier gives an attacker the opportunity to steal authenticated sessions.