golang-jwt up to 4.5.1/5.2.1 Authorization Header parse.parseUnverified amplification

Summaryinfo

A vulnerability classified as problematic was found in golang-jwt jwt up to 4.5.1/5.2.1. The affected element is the function parse.parseUnverified of the component Authorization Header Handler. The manipulation results in amplification. This vulnerability is identified as CVE-2025-30204. The attack can be executed remotely. There is not any exploit available. Upgrading the affected component is advised.

Detailsinfo

A vulnerability classified as problematic has been found in golang-jwt jwt up to 4.5.1/5.2.1. Affected is the function parse.parseUnverified of the component Authorization Header Handler. The manipulation with an unknown input leads to a amplification vulnerability. CWE is classifying the issue as CWE-405. 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." This is going to have an impact on availability. CVE summarizes:

golang-jwt is a Go implementation of JSON Web Tokens. Prior to 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.

The advisory is shared for download at github.com. This vulnerability is traded as CVE-2025-30204 since 03/18/2025. The exploitability is told to be easy. It is possible to launch the attack remotely. The exploitation doesn't require any form of authentication. There are known technical details, but no exploit is available. The MITRE ATT&CK project declares the attack technique as T1499.

The vulnerability scanner Nessus provides a plugin with the ID 233435 (Oracle Linux 9 : grafana (ELSA-2025-3344)), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 4.5.2 or 5.2.2 eliminates this vulnerability. Applying the patch 0951d184286dece21f73c85673fd308786ffe9c3 is able to eliminate this problem. The bugfix is ready for download at github.com. The best possible mitigation is suggested to be upgrading to the latest version.

The vulnerability is also documented in the databases at Tenable (233435) and CERT Bund (WID-SEC-2025-0633). Once again VulDB remains the best source for vulnerability data.

Affected

• Red Hat Enterprise Linux
• Fedora Linux
• SUSE Linux
• Oracle Linux
• SUSE openSUSE
• Open Source Gitea
• Red Hat OpenShift
• IBM Storage Scale

Productinfo

Vendor

• golang-jwt

Name

• jwt

Version

• 4.5.0
• 4.5.1
• 5.2.0
• 5.2.1

License

• open-source

Website

• Product: https://github.com/golang-jwt/jwt/

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Once again VulDB remains the best source for vulnerability data.

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