CVE-2021-41106
MEDIUMDescription
JWT is a library to work with JSON Web Token and JSON Web Signature. Prior to versions 3.4.6, 4.0.4, and 4.1.5, users of HMAC-based algorithms (HS256, HS384, and HS512) combined with `Lcobucci\JWT\Signer\Key\LocalFileReference` as key are having their tokens issued/validated using the file path as hashing key - instead of the contents. The HMAC hashing functions take any string as input and, since users can issue and validate tokens, users are lead to believe that everything works properly. Versions 3.4.6, 4.0.4, and 4.1.5 have been patched to always load the file contents, deprecated the `Lcobucci\JWT\Signer\Key\LocalFileReference`, and suggest `Lcobucci\JWT\Signer\Key\InMemory` as the alternative. As a workaround, use `Lcobucci\JWT\Signer\Key\InMemory` instead of `Lcobucci\JWT\Signer\Key\LocalFileReference` to create the instances of one's keys.
How to fix
Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.
CVSS v3 Vector
Exploitability
Impact
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N
Exploit Intelligence
Low risk: more likely to be exploited than 10% of all known CVEs.
References
Related Vulnerabilities
Other CWE-345 vulnerabilities, ordered by exploit likelihood. View all
| CVE | Severity | CVSS | EPSS | Exploited | Fix |
|---|---|---|---|---|---|
| CVE-2023-38831 | High | 7.8 | 98% | KEV + Ransom | Fix |
| CVE-2016-4553 | High | 8.6 | 80% | - | Fix |
| CVE-2016-4554 | High | 8.6 | 39% | - | Fix |
| CVE-2023-35719 | Medium | 6.8 | 26% | - | - |
| CVE-2022-26871 | Critical | 9.8 | 20% | KEV | - |
| CVE-2014-4936 | High | 9.3 | 17% | - | - |
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Start freeThis product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2025-11-18.