# CVE-2021-46743: Firebase PHP-JWT key/algorithm type confusion

Source: https://junglewise.ai/threats/cve-2021-46743-firebase-php-jwt-key-algorithm-type-confusion  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2022-03-30  
License: CC BY 4.0 with a link back

CVE-2021-46743 · Severity: low · CVSS 3.1 · Published 2022-03-30

Firebase PHP-JWT key/algorithm type confusion

Technologies: [firebase/php-jwt (Packagist)](https://junglewise.ai/threats/technologies/firebase-php-jwt). Vendors: [Packagist](https://junglewise.ai/threats/vendors/packagist).

## Quick answers

**Is CVE-2021-46743 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2021-46743 being exploited in the wild.

**How severe is CVE-2021-46743?** Low severity, with a CVSS score of 3.1, published 30 March 2022.

**Which products and versions are affected?** firebase/php-jwt (Packagist) ECOSYSTEM:introduced=0,fixed=6.0.0.

**Is there a fix for CVE-2021-46743?** Yes. firebase/php-jwt (Packagist): upgrade to 6.0.0 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**Am I affected by CVE-2021-46743?** Check whether you run firebase/php-jwt (Packagist) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- firebase/php-jwt (Packagist): upgrade to 6.0.0 or later

  ```sh
  composer require firebase/php-jwt:^6.0.0
  ```


## Affected products

- firebase/php-jwt (Packagist) ECOSYSTEM:introduced=0,fixed=6.0.0

## Identifiers

- CVE-2021-46743
- GHSA-8xf4-w7qw-pjjw

## Related threats

- [php-jwt contains weak encryption](https://junglewise.ai/threats/cve-2025-45769-php-jwt-contains-weak-encryption)
- [firebase/php-jwt: "None" Algorithm treated as valid on tokens](https://junglewise.ai/threats/firebase-php-jwt-none-algorithm-treated-as-valid-on-tokens-5fd83183)