# CVE-2026-41213

## Summary

- **CVE ID:** CVE-2026-41213
- **Severity:** MEDIUM
- **CVSS Score:** 5.9 (CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N)
- **CWE:** CWE-307, CWE-1289
- **Published:** Apr 23, 2026
- **Last Modified:** Apr 25, 2026

## Description

@node-oauth/oauth2-server is a module for implementing an OAuth2 server in Node.js. The token exchange path accepts RFC7636-invalid code_verifier values (including one-character strings) for S256 PKCE flows. Because short/weak verifiers are accepted and failed verifier attempts do not consume the authorization code, an attacker who intercepts an authorization code can brute-force code_verifier guesses online until token issuance succeeds.

## Affected Products

- node-oauth — node-oauth2-server (< 5.3.0)

## References

- [CNA](https://github.com/node-oauth/node-oauth2-server/security/advisories/GHSA-jhm7-29pj-4xvf)

## Exploitation Prediction (EPSS)

- **EPSS Score:** 0.26%
- **EPSS Percentile:** 17.5

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_Exported from OnDuty AI Vulnerability Intelligence on 2026-09-10._