GHSA-99h5-pjcv-gr6v is a high-severity (CVSS 8.6) CWE-285 vulnerability in better-auth. O3 Security confirms whether GHSA-99h5-pjcv-gr6v is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
Better Auth: Unauthenticated API key creation through api-key plugin
Real-World Exposure
How broadly this vulnerability is actually deployed: weekly install volume shows current usage, a proxy for how much of the ecosystem is exposed.
better-authnpmDescription
Summary
A critical authentication bypass was identified in the API key creation and update endpoints. An attacker could create or modify API keys for arbitrary users by supplying a victim’s user ID in the request body. Due to a flaw in how the authenticated user was derived, the endpoints could treat attacker-controlled input as an authenticated user object under certain conditions.
Details
The vulnerability originated from fallback logic used when determining the current user. When no session was present, the handler incorrectly allowed request-body data to populate the user context used for authorization decisions. Because server-side validation only executed when authentication was required, privileged fields were not properly protected. As a result, the API accepted unauthenticated requests that targeted other users.
This same pattern affected both the API key creation and update routes.
Impact
Unauthenticated attackers could generate or modify API keys belonging to any user. This granted full authenticated access as the targeted user and, depending on the user’s privileges, could lead to account compromise, access to sensitive data, or broader application takeover.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | better-auth | all versions | 1.3.26 |
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 1.3.26 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-99h5-pjcv-gr6v 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-99h5-pjcv-gr6v 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-99h5-pjcv-gr6v. 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-99h5-pjcv-gr6v in your dependencies?
O3 detects GHSA-99h5-pjcv-gr6v across npm dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.