Stored XSS Vulnerability in Better-Auth OAuth Client
CVE-2026-67333

5.1MEDIUM

Key Information:

Vendor

Better-auth

Status
Better-auth
Vendor
CVE Published:
1 August 2026

What is CVE-2026-67333?

The Better-Auth platform prior to version 1.6.13 is susceptible to a stored cross-site scripting (XSS) vulnerability due to improper validation of redirect URIs registered via deprecated plugins. An attacker can exploit this by registering an OAuth client with a malicious JavaScript redirect_uri. This redirect_uri is returned unchanged by the authorization server in the consent response. If the consent page is navigated to this redirect_URI, the attacker's JavaScript runs within the authorization server's context, potentially leading to session hijacking and account takeover for users.

Affected Version(s)

better-auth 0 < 1.6.13

better-auth 1.7.0-beta.0 < 1.7.0-beta.4

better-auth 1.6.13

References

https://github.com/better-auth/better-auth/security/advis...
vendor-advisory
https://www.vulncheck.com/advisories/better-auth-before-s...
third-party-advisory

CVSS V4

Score:
5.1
Severity:
MEDIUM
Confidentiality:
None
Integrity:
None
Availability:
None
Attack Vector:
Network
Attack Complexity:
Low
Attack Required:
None
Privileges Required:
Undefined
User Interaction:
Unknown

Timeline

  • Vulnerability published

  • Vulnerability Reserved

Credit

hillalee
.