better-auth up to 1.1.15 Error Page /api/auth/error cross site scripting

Summaryinfo

A vulnerability categorized as problematic has been discovered in better-auth up to 1.1.15. The impacted element is an unknown function of the file /api/auth/error of the component Error Page. The manipulation of the argument Error results in cross site scripting. This vulnerability is known as CVE-2025-71404. It is possible to launch the attack remotely. No exploit is available.

Detailsinfo

A vulnerability was found in better-auth up to 1.1.15. It has been classified as problematic. Affected is an unknown functionality of the file /api/auth/error of the component Error Page. The manipulation of the argument error with an unknown input leads to a cross site scripting vulnerability. CWE is classifying the issue as 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. This is going to have an impact on integrity. CVE summarizes:

better-auth versions after v0.0.2 and before 1.1.16 contain a reflected cross-site scripting (XSS) vulnerability on the /api/auth/error page, where the value of the 'error' URL parameter is reflected as HTML without proper neutralization. An attacker who coerces a user into visiting a specially-crafted URL can execute arbitrary JavaScript in the context of the user's browser. The issue is fixed in version 1.1.16.

The advisory is shared for download at github.com. This vulnerability is traded as CVE-2025-71404 since 07/18/2026. The exploitability is told to be easy. It is possible to launch the attack remotely. The exploitation doesn't require any form of authentication. Successful exploitation requires user interaction by the victim. There are known technical details, but no exploit is available. The MITRE ATT&CK project declares the attack technique as T1059.007.

Upgrading to version 1.1.16 eliminates this vulnerability.

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Productinfo

Name

• better-auth

Version

• 1.1.0
• 1.1.1
• 1.1.2
• 1.1.3
• 1.1.4
• 1.1.5
• 1.1.6
• 1.1.7
• 1.1.8
• 1.1.9
• 1.1.10
• 1.1.11
• 1.1.12
• 1.1.13
• 1.1.14
• 1.1.15

Website

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

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