CVE-2021-41106
4.4 · MEDIUMOverview
CVE-2021-41106 is a medium-severity vulnerability affecting lcobucci jwt. It was published on September 28, 2021 and has a CVSS 3.1 base score of 4.4 (MEDIUM).
This vulnerability has a CVSS 3.1 base score of 4.4, rated MEDIUM. It requires local or adjacent network access to exploit. Some level of privileges is required for exploitation.
Technical Description
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.
Remediation
Check the references section for vendor advisories and patches from lcobucci. Update jwt to the latest patched version. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.
Affected Products
| Vendor | Product | Versions | Status |
|---|---|---|---|
| lcobucci | jwt | >= 3.4.0, < 3.4.6 | Affected |
References
Frequently Asked Questions
What is CVE-2021-41106?
CVE-2021-41106 is a medium-severity vulnerability affecting lcobucci jwt. It was published on September 28, 2021 and has a CVSS 3.1 base score of 4.4 (MEDIUM).
How severe is CVE-2021-41106?
This vulnerability has a CVSS 3.1 base score of 4.4, rated MEDIUM. It requires local or adjacent network access to exploit. Some level of privileges is required for exploitation.
How do I fix or remediate CVE-2021-41106?
Check the references section for vendor advisories and patches from lcobucci. Update jwt to the latest patched version. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.
How can CyberStrike help with CVE-2021-41106?
CyberStrike's AI-powered security agents can automatically detect CVE-2021-41106 across your infrastructure using autonomous pentesting, DAST scanning, and HackBrowser. The platform continuously monitors for known vulnerabilities and provides actionable remediation guidance prioritized by real-world exploitability.
How CyberStrike Helps
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