Verification Bypass in jsonwebtoken

published 2018-05-29 8 y ago modified 2026-09-10 1 mo ago also GHSA-c7hr-j4mj-j2w6 , EUVD-2018-0569

cvss: 9.8; version 3.0, NVD
cisa kev: Not listed; not in CISA's catalog
epss: 8.4%; EPSS 8.4% chance of exploitation in 30 days, percentile 95%
public exploits: 0; none known

In jsonwebtoken node module before 4.2.2 it is possible for an attacker to bypass verification when a token digitally signed with an asymmetric key (RS/ES family) of algorithms but instead the attacker send a token digitally signed with a symmetric algorithm (HS* family).

Patch / fix

fixed in 2 links 1

npm jsonwebtoken 4.2.2
auth0 jsonwebtoken 4.2.2

github.com/auth0/node-jsonwebtoken@1bb584b commit

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2015-9235 updated 2025-11-21 cvss 7.3

nodejs-jsonwebtoken: verification step bypass with an altered token

Red Hat Mobile Application Platform 4 nodejs-jsonwebtoken
not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

Exploit prediction

8.37% chance of exploitation in the next 30 days, higher than 95% of all scored CVEs (FIRST EPSS, 2026-11-09).

Exploits and checks

timmclean.net https://www.timmclean.net/2015/02/25/jwt-alg-none.html referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by	version	score	vector
NVD	3.0	9.8	CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
NVD	2.0	7.5	AV:N/AC:L/Au:N/C:P/I:P/A:P

Affected packages

ecosystem	package	affected	fixed in
npm	jsonwebtoken	<4.2.2	4.2.2

Affected products

HackerOne jsonwebtoken node module

Classification

Weakness

CWE-20 Improper Input Validation
CWE-327 Use of a Broken or Risky Cryptographic Algorithm

References

github.com /auth0/node-jsonwebtoken/commit/1bb584bc382295eeb7ee8c4452a673a77a68b687
web, patch, third-party-advisory
timmclean.net /2015/02/25/jwt-alg-none.html
web, exploit, third-party-advisory
auth0.com /blog/2015/03/31/critical-vulnerabilities-in-json-web-token-libraries/
broken-link, vendor-advisory
nodesecurity.io /advisories/17
third-party-advisory
nvd.nist.gov /vuln/detail/CVE-2015-9235
advisory
auth0.com /blog/2015/03/31/critical-vulnerabilities-in-json-web-token-libraries
web
github.com /advisories/GHSA-c7hr-j4mj-j2w6
advisory
npmjs.com /advisories/17
web

Sources

CVE List CVE-2015-9235
GitHub Advisory GHSA-c7hr-j4mj-j2w6
NVD CVE-2015-9235

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

Summary