Affected: authlib

Authlib is a Python library which builds OAuth and OpenID Connect servers. In versions 1.0.0 through 1.6.5, cache-backed state/request-token storage is not tied to the initiating user session, so CSRF is possible for any attacker that has a valid state (easily obtainable via an attacker-initiated authentication flow). When a cache is supplied to the OAuth client registry, FrameworkIntegration.set_state_data writes the entire state blob under _state_{app}_{state}, and get_state_data ignores the caller’s session altogether. This issue has been patched in version 1.6.6.

Affected: PyPI: authlib

# Security Advisory: Cache-Backed State Storage CSRF in Authlib

The Security Labs team at Snyk has reported a security issue affecting Authlib, identified during a recent research project.

The Snyk Security Labs team has identified a vulnerability that can result in a one-click account takeover in applications that utilize the Authlib library.

## Description

Cache-backed state/request-token storage is not tied to the initiating user session, making CSRF possible for any attacker that possesses a valid state value (easily obtainable via an attacker-initiated authentication flow). When a cache is supplied to the OAuth client registry, `FrameworkIntegration.set_state_data` writes the entire state blob under `_state_{app}_{state}`, and `get_state_data` disregards the caller's session entirely. [1][2]

```py def _get_cache_data(self, key): value = self.cache.get(key) if not value: return None try: return json.loads(value) except (TypeError, ValueError): return None [snip] def get_state_data(self, session, state): key = f"_state_{self.name}_{state}" if self.cache: value = self._get_cache_data(key) else: value = session.get(key) if value: return value.get("data") return None ```

*authlib/integrations/base_client/framework_integration.py:12-41*

Retrieval in `authorize_access_token` therefore succeeds for whichever browser prese…

Affected: PyPI: authlib

# Security Advisory: Cache-Backed State Storage CSRF in Authlib

The Security Labs team at Snyk has reported a security issue affecting Authlib, identified during a recent research project.

The Snyk Security Labs team has identified a vulnerability that can result in a one-click account takeover in applications that utilize the Authlib library.

## Description

Cache-backed state/request-token storage is not tied to the initiating user session, making CSRF possible for any attacker that possesses a valid state value (easily obtainable via an attacker-initiated authentication flow). When a cache is supplied to the OAuth client registry, `FrameworkIntegration.set_state_data` writes the entire state blob under `_state_{app}_{state}`, and `get_state_data` disregards the caller's session entirely. [1][2]

```py def _get_cache_data(self, key): value = self.cache.get(key) if not value: return None try: return json.loads(value) except (TypeError, ValueError): return None [snip] def get_state_data(self, session, state): key = f"_state_{self.name}_{state}" if self.cache: value = self._get_cache_data(key) else: value = session.get(key) if value: return value.get("data") return None ```

*authlib/integrations/base_client/framework_integration.py:12-41*

Retrieval in `authorize_access_token` therefore succeeds for whichever browser prese…