Vulnerability · Published Mar 29, 2022 · Assigned by mitre

CVE-2021-46743

Critical 9.1

In plain English

A critical-severity security flaw in the firebase/php-jwt package (Packagist). There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.9% (higher than 60% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS NVD)9.1Critical

Exploit odds (30 days)0.9%top 39.7% of all CVEs

Exploited in the wildNo reportsnot in CISA KEV

Attack toolingNoneno public tooling known

Official description

In Firebase PHP-JWT before 6.0.0, an algorithm-confusion issue (e.g., RS256 / HS256) exists via the kid (aka Key ID) header, when multiple types of keys are loaded in a key ring. This allows an attacker to forge tokens that validate under the incorrect key. NOTE: this provides a straightforward way to use the PHP-JWT library unsafely, but might not be considered a vulnerability in the library itself.

Affected packages & fixed versions

Ecosystem	Package	Fixed in	Advisory
Packagist	firebase/php-jwt	6.0.0	GHSA-8xf4-w7qw-pjjw

Affected products (as reported)

Vendor	Product	Versions
n/a	n/a	n/a

References

https://github.com/firebase/php-jwt/issues/351 x_refsource_MISC