jwt-go allows excessive memory allocation during header parsing

Vulnerability Description

golang-jwt is a Go implementation of JSON Web Tokens. Starting in version 3.2.0 and prior to versions 5.2.2 and 4.5.2, the function parse.ParseUnverified splits (via a call to strings.Split) its argument (which is untrusted data) on periods. As a result, in the face of a malicious request whose Authorization header consists of Bearer followed by many period characters, a call to that function incurs allocations to the tune of O(n) bytes (where n stands for the length of the function's argument), with a constant factor of about 16. This issue is fixed in 5.2.2 and 4.5.2.

References

• https://github.com/golang-jwt/jwt/security/advisories/GHSA-mh63-6h87-95cp
• https://github.com/golang-jwt/jwt/commit/0951d184286dece21f73c85673fd308786ffe9c3
• https://github.com/golang-jwt/jwt/commit/bf316c48137a1212f8d0af9288cc9ce8e59f1afb