CVE-2025-30204: jwt-go allows excessive memory allocation during header parsing

Vulnerability summary

CVE-2025-30204 is a high (CVSS 7.5) vulnerability in golang-jwt jwt. EPSS estimates a 0.81% chance of exploitation in the next 30 days, higher than 56.9% of scored vulnerabilities.

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Timeline

1. 21-03-2025
   PublishedVulnerability first disclosed.
2. 10-04-2025
   Last modifiedVulnerability information updated.

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.

• CWE-405Asymmetric Resource Consumption (Amplification)The product does not properly control situations in which an adversary can cause the product to consume or produce excessive resources without requiring the adversary to invest equivalent work or otherwise prove authorization, i.e., the adversary's influence is "asymmetric."