CVE-2025-65025: esm.sh CDN service has arbitrary file write via tarslip

Severity: critical (CVSS 9.8 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.6% probability of exploitation in the next 30 days
Public exploit or detection template: yes
Published: 2025-11-19 · updated 2026-10-18
Weakness: CWE-22

Description

esm.sh is a nobuild content delivery network(CDN) for modern web development. Prior to version 136, the esm.sh CDN service is vulnerable to path traversal during NPM package tarball extraction. An attacker can craft a malicious NPM package containing specially crafted file paths (e.g., package/../../tmp/evil.js). When esm.sh downloads and extracts this package, files may be written to arbitrary locations on the server, escaping the intended extraction directory. This issue has been patched in version 136.

Affected products

esm-dev esm.sh: before 136 — fixed in 136

How to fix

Upgrade to a fixed version: esm-dev esm.sh 136. Check the vendor advisory for mitigations.

References

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