CVE-2026-67333
better-auth before 1.6.13 Stored XSS via javascript redirect_uri
- State
- Published
- Severity
- 5.1 Medium
- Published
- Aug 1, 2026
- Updated
- Aug 3, 2026
- Reserved
- Jul 29, 2026
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.
Scores
| CVSS | Score | Vector | Source |
|---|---|---|---|
| 4.0 | 5.1 Medium | CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:P/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N | VulnCheck |
| 3.1 | 7.2 High | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:N | VulnCheck |
Weaknesses
- CWE-79 Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
Affected Products
| Product | Versions |
|---|---|
better-authbetter-auth |
|
better-authbetter-auth |
|
References
- GitHub Security Advisory (GHSA-86j7-9j95-vpqj)vendor-advisory
- VulnCheck Advisory: better-auth before 1.6.13 Stored XSS via javascript redirect_urithird-party-advisory
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