Vulnerability Description
better-auth before 1.6.13 (and pre-release builds 1.7.0-beta.0 through 1.7.0-beta.3) fail to validate the scheme of redirect_uris registered via the deprecated oidc-provider plugin and the mcp plugin (which wraps the same provider). An attacker can register an OAuth client with a javascript: redirect_uri, which the authorization server later returns unchanged in the consent response. If the deployment's consent page navigates the browser to the returned redirectURI (e.g. assigning it to window.location.href), the attacker's JavaScript executes in the authorization-server origin, exposing the victim's session and enabling account takeover.
CVSS Score
HIGH
Related Weaknesses (CWE)
References
- https://github.com/better-auth/better-auth/security/advisories/GHSA-86j7-9j95-vp
- https://www.vulncheck.com/advisories/better-auth-before-stored-xss-via-javascrip
FAQ
What is CVE-2026-67333?
CVE-2026-67333 is a vulnerability with a CVSS score of 7.2 (HIGH). better-auth before 1.6.13 (and pre-release builds 1.7.0-beta.0 through 1.7.0-beta.3) fail to validate the scheme of redirect_uris registered via the deprecated oidc-provider plugin and the mcp plugin ...
How severe is CVE-2026-67333?
CVE-2026-67333 has been rated HIGH with a CVSS base score of 7.2/10. Review the CVSS metrics above for detailed severity breakdown.
Is there a patch for CVE-2026-67333?
Check the references section above for vendor advisories and patch information. Review vendor security bulletins for remediation guidance.