better-auth up to 1.1.5 Email Verification callbackURL redirect

Summaryinfo

A vulnerability identified as problematic has been detected in better-auth up to 1.1.5. Affected by this vulnerability is an unknown functionality of the component Email Verification Handler. This manipulation of the argument callbackURL causes redirect. This vulnerability is registered as CVE-2024-56734. Remote exploitation of the attack is possible. No exploit is available. You should upgrade the affected component.

Detailsinfo

A vulnerability has been found in better-auth up to 1.1.5 and classified as problematic. Affected by this vulnerability is some unknown functionality of the component Email Verification Handler. The manipulation of the argument callbackURL with an unknown input leads to a redirect vulnerability. The CWE definition for the vulnerability is CWE-601. A web application accepts a user-controlled input that specifies a link to an external site, and uses that link in a Redirect. This simplifies phishing attacks. As an impact it is known to affect integrity. The summary by CVE is:

Better Auth is an authentication library for TypeScript. An open redirect vulnerability has been identified in the verify email endpoint of all versions of Better Auth prior to v1.1.6, potentially allowing attackers to redirect users to malicious websites. This issue affects users relying on email verification links generated by the library. The verify email callback endpoint accepts a `callbackURL` parameter. Unlike other verification methods, email verification only uses JWT to verify and redirect without proper validation of the target domain. The origin checker is bypassed in this scenario because it only checks for `POST` requests. An attacker can manipulate this parameter to redirect users to arbitrary URLs controlled by the attacker. Version 1.1.6 contains a patch for the issue.

It is possible to read the advisory at github.com. This vulnerability is known as CVE-2024-56734 since 12/27/2024. 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. Technical details of the vulnerability are known, but there is no available exploit. The attack technique deployed by this issue is T1204.001 according to MITRE ATT&CK.

Upgrading to version 1.1.6 eliminates this vulnerability. Applying the patch deb3d73aea90d0468d92723f4511542b593e522f is able to eliminate this problem. The bugfix is ready for download at github.com. The best possible mitigation is suggested to be upgrading to the latest version.

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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

License

• open-source

Website

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

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