esm.sh is vulnerable to full-response SSRF

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS 4.0

8.7 · CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N · score source

EPSS

• CVE-2025-50180: 0.44% estimated exploitation activity in the next 30 days; percentile 38.05 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Summary esh.sh is vulnerable to a full-response SSRF, allowing an attacker to retrieve information from internal websites through the vulnerability. Details Vulnerable code location: https://github.com/esm-dev/esm.sh/blob/f80ff8c8d58749e77fa964abde468fc61f8bd89e/server/router.go#L511 If the internal address has a suffix listed below, the attacker can obtain content from the specified internal address. eg: https://esm.sh/https://local.site/test.md A 302 redirect can be used to bypass the suffix restriction. eg: https://esm.sh/https://attacker.site/test.md https://attacker.site/test.md 302 redirect to http://169.254.169.254/v1.json PoC Use Flask to start a server that returns a 302 redirect. Let esh.sh visit this site. https://esm.sh/https://attacker.site/test.md Attacker can obtain data from http://169.254.169.254/v1.json. Decode the data (redacted) . Impact An attacker can exploit the vulnerability to access internal sites, and in a cloud environment, can retrieve access keys (AK)…

Published by the source

25 Feb 2026, 15:19 UTC

Last modified by the source

27 Feb 2026, 20:56 UTC

Source last checked

26 Oct 2026, 15:14 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-3c9r-837r-qqm4

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# Patch Next advisory brief: CVE-2025-50180

Advisory: esm.sh is vulnerable to full-response SSRF
IDs: CVE-2025-50180, GHSA-3c9r-837r-qqm4
Record: https://patchnext.com/advisories/cve-2025-50180 (revision 1, source checked 26 Oct 2026, 15:14 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 8.7)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: github.com/esm-dev/esm.sh 0.0.0-20250616164159-0593516c4cfa. A vendor fix does not mean a deployment is fixed.

## Affected components
- Go github.com/esm-dev/esm.sh: affected < 0.0.0-20250616164159-0593516c4cfa; fixed in 0.0.0-20250616164159-0593516c4cfa

## Suggested inspection (read-only)
- Go github.com/esm-dev/esm.sh: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on github.com/esm-dev/esm.sh.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-3c9r-837r-qqm4 (GitHub-reviewed advisory GHSA-3c9r-837r-qqm4 lists affected ranges: Go github.com/esm-dev/esm.sh >=0 <0.0.0-20250616164159-0593516c4cfa)

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