CVE-2025-59342CWE-24

esm.sh writes arbitrary files via path traversal in `X-Zone-Id` header

Medium · published September 17, 2025

CVSS v4.0
5.5
EPSS
3%
Percentile
87.3
In the wild
Unconfirmed
What it is

esm.sh is a nobuild content delivery network(CDN) for modern web development. In 136 and earlier, 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. Version 136.1 contains a patch.

The record
Technical detail
CVSS v4.0
5.5 · MEDIUM
Vector
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:P
EPSS
0.03006 · 87.3th percentile
Weakness
CWE-24 · Path Traversal: '../filedir'
Published
2025-09-17T17:59Z
EPSS history
Timeline
  • 17 SEP 17:59Z
    esm.sh writes arbitrary files via path traversal in `X-Zone-Id` header
    cvelistv5