Headline
CVE-2023-32682: Improper checks for deactivated users during login
Synapse is a Matrix protocol homeserver written in Python with the Twisted framework. In affected versions it may be possible for a deactivated user to login when using uncommon configurations. This only applies if any of the following are true: 1. JSON Web Tokens are enabled for login via the jwt_config.enabled configuration setting. 2. The local password database is enabled via the password_config.enabled and password_config.localdb_enabled configuration settings and a user’s password is updated via an admin API after a user is deactivated. Note that the local password database is enabled by default, but it is uncommon to set a user’s password after they’ve been deactivated. Installations that are configured to only allow login via Single Sign-On (SSO) via CAS, SAML or OpenID Connect (OIDC); or via an external password provider (e.g. LDAP) are not affected. If not using JSON Web Tokens, ensure that deactivated users do not have a password set. This issue has been addressed in version 1.85.0. Users are advised to upgrade.
Impact
It may be possible for a deactivated user to login when using uncommon configurations.
This only applies if any of the following are true:
- JSON Web Tokens are enabled for login via the jwt_config.enabled configuration setting
- The local password database is enabled via the password_config.enabled and password_config.localdb_enabled configuration settings and a user’s password is updated via an admin API after a user is deactivated.
Note that the local password database is enabled by default, but it is uncommon to set a user’s password after they’ve been deactivated.
Installations that are configured to only allow login via Single Sign-On (SSO) via CAS, SAML or OpenID Connect (OIDC); or via an external password provider (e.g. LDAP) are not affected.
Patches
- If using JSON Web Token logins: #15624
- For other users: #15634
Workarounds
If not using JSON Web Tokens, ensure that deactivated users do not have a password set. This list of users can be queried from PostgreSQL:
SELECT name FROM users WHERE password_hash IS NOT NULL AND deactivated = 1;
Related news
### Impact It may be possible for a deactivated user to login when using uncommon configurations. This only applies if any of the following are true: * [JSON Web Tokens are enabled for login](https://matrix-org.github.io/synapse/latest/jwt.html) via the `jwt_config.enabled` configuration setting * The [local password database is enabled](https://matrix-org.github.io/synapse/latest/usage/configuration/config_documentation.html#password_config) via the `password_config.enabled` and `password_config.localdb_enabled` configuration settings *and* a user's password is [updated via an admin API](https://matrix-org.github.io/synapse/latest/admin_api/user_admin_api.html#create-or-modify-account) after a user is deactivated. **Note that the local password database is enabled by default**, but it is uncommon to set a user's password after they've been deactivated. Installations that are configured to only allow login via Single Sign-On (SSO) via CAS, SAML or OpenID Connect (OIDC); or via an e...