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-oauth\/oauth2-server
References2
- github.com/node-oauth/node-oauth2-server/security/advisories/GH… ExploitMitigationVendor Advisory
- github.com/node-oauth/node-oauth2-server/security/advisories/GH… ExploitMitigationVendor Advisory
Metrics
- CVSS 3.1
-
5.9
MEDIUM
Score source: CNA
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N - EPSS — exploit probability
- 0% percentile: 18 · as of 13 November 2026
- CWE
- CWE-307CWE-1289
Could this be exploited in your environment?
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