Zulip is an open-source team collaboration tool. In Zulip Server versions through 12.1, GenericOpenIdConnectBackend matches the identity provider email claim to an active accounts delivery_email without rejecting an explicitly false email_verified claim. If a configured identity provider returns an email address that the authenticating user does not control together with email_verified=false, Zulip can log the user into the existing account for that address. Exploitation requires a misconfigured trusted identity provider, and deployments whose authoritative identity provider only emits email addresses controlled by the authenticating user are not affected. This issue is fixed in version 12.2.
Weakness
When an actor claims to have a given identity, the product does not prove or insufficiently proves that the claim is correct.
Potential Mitigations
Related Attack Patterns
- https://cwe.mitre.org/data/definitions/114.html
- https://cwe.mitre.org/data/definitions/115.html
- https://cwe.mitre.org/data/definitions/151.html
- https://cwe.mitre.org/data/definitions/194.html
- https://cwe.mitre.org/data/definitions/22.html
- https://cwe.mitre.org/data/definitions/57.html
- https://cwe.mitre.org/data/definitions/593.html
- https://cwe.mitre.org/data/definitions/633.html
- https://cwe.mitre.org/data/definitions/650.html
- https://cwe.mitre.org/data/definitions/94.html
References
- https://github.com/zulip/zulip/commit/68d2d9defa39f8af96a50fc7430efc34dee120b5
- https://github.com/zulip/zulip/commit/b40f191a8c71e74fcb471f71de6a1233de157102
- https://github.com/zulip/zulip/pull/39913
- https://github.com/zulip/zulip/releases/tag/12.2
- https://github.com/zulip/zulip/security/advisories/GHSA-xw9h-9rcm-hx4m