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

Advisory record · `GHSA-wmjr-v86c-m9jj`

- **Identifiers:** `GHSA-wmjr-v86c-m9jj` · `CVE-2025-71402`
- **State:** Confirmed
- **Severity:** CVSS 2.0 Low
- **Critical:** No
- **Weakness (CWE):** [CWE-287](https://cwe.mitre.org/data/definitions/287.html) · [CWE-345](https://cwe.mitre.org/data/definitions/345.html) · [CWE-347](https://cwe.mitre.org/data/definitions/347.html)
- **Tags:** [Authentication bypass](https://agentprime.io/advisories/tag/auth-bypass.md) · [Weak cryptography or TLS](https://agentprime.io/advisories/tag/weak-crypto.md) · [CWE-345](https://agentprime.io/advisories/tag/cwe-345.md)
- **Published:** 26 Nov 2025
- **Updated:** 2 Aug 2026
- **Reviewed by a person:** No

Published by the GitHub Advisory Database at 26 Nov 2025, 22:11 UTC. agentprime has not analysed this yet, so whether it affects any app is not known.

## Affected packages

- `better-auth` (npm): affected `>=1.3.34, <1.4.0`; fixed in `1.4.0`

## Not analysed yet

We haven’t published our analysis of this Advisory yet. Once a person has reviewed it, this page will say what’s vulnerable, what has to be true for your app to be affected, and how to check.

## Severity and exploitation

- 2.0 Low, CVSS 4.0: `CVSS:4.0/AV:N/AC:L/AT:P/PR:H/UI:P/VC:L/VI:L/VA:L/SC:L/SI:L/SA:N`, from CNA (VulnCheck)

- **CISA KEV:** Not listed.
- **EPSS:** 0.0027, the 19th percentile, on 10 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

## Timeline

This record came from the full history of the GitHub Advisory Database, published 26 Nov 2025. New records show when each source confirmed them.

## Sources

- [GitHub Advisory Database: GHSA-wmjr-v86c-m9jj](https://github.com/advisories/GHSA-wmjr-v86c-m9jj)
- [OSV: GHSA-wmjr-v86c-m9jj](https://osv.dev/vulnerability/GHSA-wmjr-v86c-m9jj)
- <https://github.com/better-auth/better-auth/security/advisories/GHSA-wmjr-v86c-m9jj>
- <https://github.com/better-auth/better-auth/commit/cfc453a2a6eb02951f9a0a7c944064936e73eee8>
- <https://github.com/better-auth/better-auth>
- <https://github.com/better-auth/better-auth/releases/tag/v1.4.0>

Facts on this page come from the GitHub Advisory Database (CC-BY 4.0), OSV and the other sources listed, as published. We don’t reproduce full advisory descriptions, which can contain exploit code.

## Check whether this affects you

A Match means an installed version is in the affected range above. Most don’t affect the app; agentprime hasn’t analysed this one yet.

- With the agentprime MCP server (<https://api.agentprime.io/mcp>), ask your agent to check the project: `check_lockfile` sends a lockfile, `check_packages` a list of installed packages, and both return the Matches and the upgrades that clear them. `get_advisory` returns this record. Setup: <https://agentprime.io/mcp.md>
- In a browser: <https://agentprime.io/check/> reads your lockfile in the browser, never uploading it.
- Whether it touches your code, with file and line: the Claude Code plugin, <https://agentprime.io/plugin.md>
- As JSON: <https://api.agentprime.io/v1/advisories/GHSA-wmjr-v86c-m9jj>, or `POST https://api.agentprime.io/v1/match` with your packages (<https://agentprime.io/api.md>)

---

The web page: <https://agentprime.io/advisories/GHSA-wmjr-v86c-m9jj/>. Everything for agents: <https://agentprime.io/llms.txt>.