GHSA-8jhw-6pjj-8723
Better Auth has an Open Redirect Vulnerability in Verify Email Endpoint
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
Blast Radius
better-authReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects npm packages — download data is not available via public APIs for these ecosystems.
Description
Summary
An open redirect vulnerability has been identified in the verify email endpoint of Better Auth, potentially allowing attackers to redirect users to malicious websites. This issue affects users relying on email verification links generated by the library.
Affected Versions
- All versions prior to v1.1.6.
Impact
Attackers could craft malicious email verification links that exploit the redirect functionality to send users to untrusted domains. This can result in:
- Phishing attacks – Users may unknowingly enter sensitive information on fake login pages.
- Reputation damage – Trust issues for applications using Better Auth.
Vulnerability Details
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.
Example Exploit:
https://example.com/auth/verify-email?token=abcd1234&callbackURL=https://malicious-site.com
Patches
Upgrade to Better Auth v1.1.6 or later. This version enforces domain validation for callbackURL for /verify-email path and for all other GET endpoints.
Workarounds
You can also use hooks to pre-check URLs in your auth instance to prevent this without upgrading:
const auth = betterAuth({
hooks: {
before: (ctx) => {
if (ctx.path === "/verify-email") {
const callbackURL = ctx.query.callbackURL; // Check if this is a trusted callback URL or not
}
}
}
})
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | better-auth | all versions | 1.1.6 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for better-auth. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update better-auth to 1.1.6 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-8jhw-6pjj-8723 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether GHSA-8jhw-6pjj-8723 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to GHSA-8jhw-6pjj-8723. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is GHSA-8jhw-6pjj-8723 in your dependencies?
O3 detects GHSA-8jhw-6pjj-8723 across npm dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.