Summary
The better-auth /api/auth/error page was vulnerable to HTML injection, resulting in a reflected cross-site scripting (XSS) vulnerability.
Details
The value of error URL parameter was reflected as HTML on the error page: https://github.com/better-auth/better-auth/blob/05ada0b79dbcac93cc04ceb79b23ca598d07830c/packages/better-auth/src/api/routes/error.ts#L81
Impact
An attacker who exploited this vulnerability by coercing a user to visit a specially-crafted URL could execute arbitrary JavaScript in the context of the user's browser.
Untrusted input is rendered as active markup in a victim's browser, which can run script in their session. Typical impact: session or credential theft, and actions taken as the user.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
Remediation advice
Kodem Kai can prioritize this vulnerability in your dependency tree and generate a fix recommendation.
Frequently Asked Questions
- What is GHSA-9X4V-XFQ5-M8X5? GHSA-9X4V-XFQ5-M8X5 is a medium-severity cross-site scripting (XSS) vulnerability in better-auth (npm), affecting versions >= 0.0.2, < 1.1.16. It is fixed in 1.1.16. Untrusted input is rendered as active markup in a victim's browser, which can run script in their session.
- Which versions of better-auth are affected by GHSA-9X4V-XFQ5-M8X5? better-auth (npm) versions >= 0.0.2, < 1.1.16 is affected.
- Is there a fix for GHSA-9X4V-XFQ5-M8X5? Yes. GHSA-9X4V-XFQ5-M8X5 is fixed in 1.1.16. Upgrade to this version or later.
- Is GHSA-9X4V-XFQ5-M8X5 exploitable, and should I be worried? Whether GHSA-9X4V-XFQ5-M8X5 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether GHSA-9X4V-XFQ5-M8X5 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
- How do I fix GHSA-9X4V-XFQ5-M8X5? Upgrade
better-authto 1.1.16 or later.