CVE-2026-41213Public exploitNetwork attack vector

Token theft via weak PKCE verifier validation

Published Apr 23, 2026 · Updated Apr 23, 2026

PKCE validation flaws in @node-oauth/oauth2-server before 5.3.0 allow remote attackers to redeem intercepted authorization codes. The token path hashes any nonempty S256 code_verifier in lib/pkce/pkce.js without enforcing the RFC 7636 length and character rules, and failed comparisons occur before code revocation. Exploitation requires an intercepted code tied to a short or predictable verifier and yields bearer tokens after repeated online guesses without altering data or interrupting service.

CVSS severity5.9
Medium
EPSS probability0.26%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

PKCE validation flaws in @node-oauth/oauth2-server before 5.3.0 allow remote attackers to redeem intercepted authorization codes. The token path hashes any nonempty S256 code_verifier in lib/pkce/pkce.js without enforcing the RFC 7636 length and character rules, and failed comparisons occur before code revocation. Exploitation requires an intercepted code tied to a short or predictable verifier and yields bearer tokens after repeated online guesses without altering data or interrupting service.

The record

CVE
CVE-2026-41213
Published
Apr 23, 2026
Updated
Apr 23, 2026
Vendor
node-oauth
Product
@node-oauth/oauth2-server
Classifications
CWE-307, CWE-1289, T1528
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Apr 23, 2026CVE publishedPublication date reported by the CVE source.
  2. Apr 23, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=< 5.3.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

node-oauth · @node-oauth/oauth2-serverversion=< 5.3.0

Published CVSS scores

5.9GitHubCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-307Improper Restriction of Excessive Authentication Attempts
CWE-1289Improper Validation of Unsafe Equivalence in Input
T1528Steal Application Access Token

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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