better-auth up to 1.6.20 cross site scripting

Summaryinfo

A vulnerability has been found in better-auth up to 1.6.20 and classified as problematic. Affected by this vulnerability is an unknown functionality. This manipulation causes cross site scripting. This vulnerability is tracked as CVE-2026-67328. The attack is possible to be carried out remotely. No exploit exists.

Detailsinfo

A vulnerability was found in better-auth up to 1.6.20. It has been declared as problematic. Affected by this vulnerability is an unknown part. The manipulation with an unknown input leads to a cross site scripting vulnerability. The CWE definition for the vulnerability is CWE-79. The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users. As an impact it is known to affect integrity. The summary by CVE is:

@better-auth/sso versions before 1.6.21 contain multiple authentication bypass vulnerabilities in SSO provider handling that allow attackers to sign in as arbitrary users. Attackers can exploit domain verification parsing mismatches, orphaned provider accounts, unbound SAML assertions, or reflected XSS on logout endpoints to gain unauthorized session access and account takeover.

The advisory is shared at github.com. This vulnerability is known as CVE-2026-67328 since 07/29/2026. The exploitation appears to be easy. The attack can be launched remotely. The exploitation doesn't need any form of authentication. It demands that the victim is doing some kind of user interaction. Neither technical details nor an exploit are publicly available. MITRE ATT&CK project uses the attack technique T1059.007 for this issue.

Upgrading to version 1.6.21 eliminates this vulnerability.

Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

Productinfo

Name

• better-auth

Version

• 1.6.0
• 1.6.1
• 1.6.2
• 1.6.3
• 1.6.4
• 1.6.5
• 1.6.6
• 1.6.7
• 1.6.8
• 1.6.9
• 1.6.10
• 1.6.11
• 1.6.12
• 1.6.13
• 1.6.14
• 1.6.15
• 1.6.16
• 1.6.17
• 1.6.18
• 1.6.19
• 1.6.20

Website

• Product: https://github.com/better-auth/better-auth/

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Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

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