How severe is GHSA-wmjr-v86c-m9jj?

No CVSS score has been assigned to GHSA-wmjr-v86c-m9jj yet. Review the advisory details and affected package list to assess your exposure.

Which packages are affected by GHSA-wmjr-v86c-m9jj?

GHSA-wmjr-v86c-m9jj affects the following packages: better-auth (npm). Ecosystems affected: npm.

How do I fix GHSA-wmjr-v86c-m9jj?

Update better-auth to 1.4.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-wmjr-v86c-m9jj is resolved across your whole dependency graph.

How do I detect GHSA-wmjr-v86c-m9jj in my npm dependencies?

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.

How do I mitigate GHSA-wmjr-v86c-m9jj if there is no patch (or I can't update yet)?

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 does O3 Security protect against GHSA-wmjr-v86c-m9jj?

O3 pinpoints whether GHSA-wmjr-v86c-m9jj is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.

Is GHSA-wmjr-v86c-m9jj actively exploited in the wild?

No public exploit code has been indexed for GHSA-wmjr-v86c-m9jj yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

When was GHSA-wmjr-v86c-m9jj published, and has it been updated?

GHSA-wmjr-v86c-m9jj was published on November 26, 2025 and was last updated on May 8, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

📦 npm

GHSA-wmjr-v86c-m9jj

Better Auth's multi-session sign-out hook allows forged cookies to revoke arbitrary sessions

Published

Nov 26, 2025

Updated

May 8, 2026

Affected

1 pkg

Patched

1 / 1

Exploits

None indexed

Blast Radius

1 pkg affected

Weekly download volume for affected packages — a proxy for how broadly this vulnerability is deployed.

better-authnpm

4.5Mdownloads / week

Description

Summary

A vulnerability was identified in the multi-session plugin for Better Auth, specifically in the /sign-out after-hook. The hook trusts raw multi-session cookies and forwards the extracted values directly to internalAdapter.deleteSessions without verifying the cookie signature. Because cookie values are not validated with getSignedCookie (or any equivalent check), an attacker can supply a forged _multi-* cookie to trigger deletion of arbitrary session tokens.

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
📦npm	`better-auth`	≥ 1.3.34&&< 1.4.0	1.4.0

Detection & mitigation playbook

Open-source dependency

Detect
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 1.4.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-wmjr-v86c-m9jj 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-wmjr-v86c-m9jj 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-wmjr-v86c-m9jj. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.

Frequently Asked Questions

### Summary A vulnerability was identified in the multi-session plugin for Better Auth, specifically in the /sign-out after-hook. The hook trusts raw multi-session cookies and forwards the extracted values directly to internalAdapter.deleteSessions without verifying the cookie signature. Because cookie values are not validated with getSignedCookie (or any equivalent check), an attacker can supply a forged _multi-* cookie to trigger deletion of arbitrary session tokens.

O3 Security · Impact-Aware SCA

Is GHSA-wmjr-v86c-m9jj in your dependencies?

O3 detects GHSA-wmjr-v86c-m9jj across npm dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.

Scan my dependencies How O3 SCA works