CVE-2026-41213

@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.

Scoring

Severity
MEDIUM
CVSS base score
5.9
CVSS vector
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N
EPSS probability
0.26%
CWE
CWE-307, CWE-1289
Published
2026-04-23
Last modified
2026-04-25

Affected products

Weakness type

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