What’s Vulnerable › Vulnerabilities

CVE-2015-9235

• Severity: critical (CVSS 9.8 v3.0)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 8.5% probability of exploitation in the next 30 days
• Public exploit or detection template: yes
• Published: 2018-05-29 · updated 2026-06-17
• Weakness: CWE-20

Description

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).

Affected products

• auth0 node-jsonwebtoken: before 4.2.2 — fixed in 4.2.2

How to fix

Upgrade to a fixed version: auth0 node-jsonwebtoken 4.2.2. Check the vendor advisory for mitigations.

References

• https://auth0.com/blog/2015/03/31/critical-vulnerabilities-in-json-web-token-libraries/
• https://github.com/auth0/node-jsonwebtoken/commit/1bb584bc382295eeb7ee8c4452a673a77a68b687
• https://nodesecurity.io/advisories/17
• https://www.timmclean.net/2015/02/25/jwt-alg-none.html
• https://auth0.com/blog/2015/03/31/critical-vulnerabilities-in-json-web-token-libraries/
• https://github.com/auth0/node-jsonwebtoken/commit/1bb584bc382295eeb7ee8c4452a673a77a68b687
• https://nodesecurity.io/advisories/17
• https://www.timmclean.net/2015/02/25/jwt-alg-none.html

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