Zulip is an open-source team collaboration tool

Why it is Amber

• CVSS 9.1 critical
• Remotely exploitable without logging in

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

Original description

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 account's 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.