Forgeable Public/Private Tokens in jwt-simple
Affected versions of the jwt-simple package allow users to select what algorithm the server will use to verify a provided JWT. A malicious actor can use this behaviour to arbitrarily modify the contents of a JWT while still passing verification. For the common use case of the JWT, the end result is a complete authentication bypass with minimal effort.
Recommendation
Update to version 0.3.1 or later.
Additionally, be sure to always specify an algorithm in calls to .decode().
Affected software
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| Platform | Package | Vulnerable versions | Fixed in |
|---|---|---|---|
| npm package | jwt-simple | < 0.3.1 | 0.3.1 |
References
- https://nvd.nist.gov/vuln/detail/CVE-2016-10555
- https://github.com/hokaccha/node-jwt-simple/pull/14
- https://github.com/hokaccha/node-jwt-simple/pull/16
- https://github.com/hokaccha/node-jwt-simple/commit/957957cfa44474049b4603b293569588ee9ffd97
- https://auth0.com/blog/2015/03/31/critical-vulnerabilities-in-json-web-token-libraries
- https://www.npmjs.com/advisories/87
- Weakness (CWE)
CWE-20- Platform
- npm
- Package
jwt-simple- Disclosed
- 06.11.2018
- Updated
- 11.10.2026 10:22
Sources and licenses
OSV / GitHub Advisory Database - GHSA-vgrx-w6rg-8fqf - CC BY 4.0
Vulnerability history: jwt-simple
All published vulnerabilities of this package (npm package), newest first. Shows whether this is a one-off slip or a package that needs watching.
- Total entries
- 2
- First → latest
- 11.2018 06.2019
- Without a fix
- 0
- Exploited in attacks
- 0
Severity breakdown
- Critical 1
- High 1
Disclosures per year
- 2018: 1
- 2019: 1
- 2020: 0
- 2021: 0
- 2022: 0
- 2023: 0
- 2024: 0
- 2025: 0
- 2026: 0
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