How severe is GHSA-mh63-6h87-95cp?

GHSA-mh63-6h87-95cp has a CVSS score of 7.5/10, rated HIGH. Immediate patching is strongly recommended.

Which packages are affected by GHSA-mh63-6h87-95cp?

GHSA-mh63-6h87-95cp affects the following packages: github.com/golang-jwt/jwt/v5 (Go), github.com/golang-jwt/jwt/v4 (Go), github.com/golang-jwt/jwt (Go). Ecosystems affected: Go.

How do I fix GHSA-mh63-6h87-95cp?

Update github.com/golang-jwt/jwt/v5 to 5.2.2 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-mh63-6h87-95cp is resolved across your whole dependency graph.

How do I detect GHSA-mh63-6h87-95cp in my Go dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/golang-jwt/jwt/v5. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.

How do I mitigate GHSA-mh63-6h87-95cp if there is no patch (or I can't update yet)?

If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

How does O3 Security protect against GHSA-mh63-6h87-95cp?

O3 pinpoints whether GHSA-mh63-6h87-95cp is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.

Is GHSA-mh63-6h87-95cp actively exploited in the wild?

No public exploit code has been indexed for GHSA-mh63-6h87-95cp yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What is the EPSS score for GHSA-mh63-6h87-95cp?

GHSA-mh63-6h87-95cp has an EPSS (Exploit Prediction Scoring System) score of 0.7%, placing it in the 48th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is GHSA-mh63-6h87-95cp?

GHSA-mh63-6h87-95cp is classified as CWE-405 (CWE-405). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

When was GHSA-mh63-6h87-95cp published, and has it been updated?

GHSA-mh63-6h87-95cp was published on March 21, 2025 and was last updated on February 4, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

🐹 Go

GHSA-mh63-6h87-95cp

HIGH

jwt-go allows excessive memory allocation during header parsing

Also known asCVE-2025-30204GO-2025-3553

Published

Mar 21, 2025

Updated

Feb 4, 2026

Affected

3 pkgs

Patched

2 / 3

Exploits

None indexed

EPSS Exploitation Probability

via FIRST.org ↗

0.7%probability of exploitation in next 30 days

Lower Risk48th percentile+0.61%

EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.

Blast Radius

3 pkgs affected

🐹github.com/golang-jwt/jwt/v5🐹github.com/golang-jwt/jwt/v4🐹github.com/golang-jwt/jwt

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects Go packages — download data is not available via public APIs for these ecosystems.

Description

Summary

Function parse.ParseUnverified currently 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. Relevant weakness: CWE-405: Asymmetric Resource Consumption (Amplification)

Details

See parse.ParseUnverified

Impact

Excessive memory allocation

Affected Packages

3 total 2 fixed

Ecosystem	Package	Vulnerable range	Fix
🐹Go	`github.com/golang-jwt/jwt/v5`	≥ 5.0.0-rc.1&&< 5.2.2	5.2.2
🐹Go	`github.com/golang-jwt/jwt/v4`	all versions	4.5.2
🐹Go	`github.com/golang-jwt/jwt`	≥ 3.2.0	No fix

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/golang-jwt/jwt/v5. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update github.com/golang-jwt/jwt/v5 to 5.2.2 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-mh63-6h87-95cp is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether GHSA-mh63-6h87-95cp is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.

Tailored to GHSA-mh63-6h87-95cp. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.

Frequently Asked Questions

### Summary Function [`parse.ParseUnverified`](https://github.com/golang-jwt/jwt/blob/c035977d9e11c351f4c05dfeae193923cbab49ee/parser.go#L138-L139) currently splits (via a call to [strings.Split](https://pkg.go.dev/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. Relevant weaknes

O3 Security · Impact-Aware SCA

Is GHSA-mh63-6h87-95cp in your dependencies?

O3 detects GHSA-mh63-6h87-95cp across Go dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.

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