Vulnerability Description
Coop is an open source review and moderation tool from ROOST. Prior to 1.0.2, the SAML strategy's verify callback resolved the authenticated user by email alone using `kyselyUserFindByEmail`, without binding the lookup to the organization in `/saml/login/:orgId/callback`. An attacker who administers an organization and controls its SAML IdP signing key can submit an assertion for a victim email to another organization's callback when that target organization has registered the same signing certificate. The assertion verifies against the target certificate, and the email resolves to the target user, creating a session as that user and allowing full cross-tenant account takeover without privileges in the target organization. Exploitation requires the unusual configuration in which the target certificate matches a signing key controlled by the attacker. This issue is fixed in version 1.0.2.
Related Weaknesses (CWE)
References
- https://github.com/roostorg/coop/commit/d1be81b6b33abc1162ee6b9952d4bd1ca761b071
- https://github.com/roostorg/coop/pull/783
- https://github.com/roostorg/coop/releases/tag/1.0.2
- https://github.com/roostorg/coop/security/advisories/GHSA-2v93-383c-9fw2
FAQ
What is CVE-2026-63398?
CVE-2026-63398 is a documented vulnerability. Coop is an open source review and moderation tool from ROOST. Prior to 1.0.2, the SAML strategy's verify callback resolved the authenticated user by email alone using `kyselyUserFindByEmail`, without ...
How severe is CVE-2026-63398?
CVSS scoring is not yet available for CVE-2026-63398. Check NVD for updates.
Is there a patch for CVE-2026-63398?
Check the references section above for vendor advisories and patch information. Review vendor security bulletins for remediation guidance.