CVE-2025-50180: esm.sh is vulnerable to full-response SSRF

Severity: high (CVSS 7.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.4% probability of exploitation in the next 30 days
Public exploit or detection template: yes
Published: 2026-02-25 · updated 2026-06-17
Weakness: CWE-918

Description

esm.sh is a no-build content delivery network (CDN) for web development. In version 136, esm.sh is vulnerable to a full-response SSRF, allowing an attacker to retrieve information from internal websites through the vulnerability. Version 137 fixes the vulnerability.

Affected products

esm-dev esm.sh: before 137 — fixed in 137

How to fix

Upgrade to a fixed version: esm-dev esm.sh 137. Check the vendor advisory for mitigations.

References

https://github.com/esm-dev/esm.sh/blob/f80ff8c8d58749e77fa964abde468fc61f8bd89e/internal/fetch/fetch.go#L13
https://github.com/esm-dev/esm.sh/blob/f80ff8c8d58749e77fa964abde468fc61f8bd89e/server/router.go#L511
https://github.com/esm-dev/esm.sh/commit/0593516c4cfab49ad3b4900416a8432ff2e23eb0
https://github.com/esm-dev/esm.sh/pull/1149
https://github.com/esm-dev/esm.sh/releases/tag/v137
https://github.com/esm-dev/esm.sh/security/advisories/GHSA-3c9r-837r-qqm4

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