CVE-2026-41213: @node-oauth/oauth2-server: PKCE code_verifier ABNF not enforced in token exchange allows brute-force redemption of intercepted authorization codes
@node-oauth/oauth2-server is a module for implementing an OAuth2 server in Node.js. The token exchange path accepts RFC7636-invalid codeverifier 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 codeverifier guesses online until token issuance succeeds.
Affected Software
Event History
Frequently Asked Questions
What is the severity of CVE-2026-41213?
CVE-2026-41213 is considered a high severity vulnerability due to its impact on the security of authorization code exchanges.
How do I fix CVE-2026-41213?
To fix CVE-2026-41213, update the @node-oauth/oauth2-server module to the latest version that enforces PKCE code_verifier validation.
What kind of attack does CVE-2026-41213 allow?
CVE-2026-41213 allows attackers to perform brute-force attacks to redeem intercepted authorization codes due to inadequate validation of code_verifier values.
Is CVE-2026-41213 a module-specific vulnerability?
Yes, CVE-2026-41213 specifically affects the @node-oauth/oauth2-server module used in Node.js applications.
What are the potential consequences of CVE-2026-41213?
The potential consequences of CVE-2026-41213 include unauthorized access to user data and services through compromised token exchanges.