CVE-2025-59342 – esm.sh writes arbitrary files via path traversal in `X-Zone-Id` header

CVE ID : CVE-2025-59342

Published : Sept. 17, 2025, 6:15 p.m. | 44 minutes ago

Description : 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.

Severity: 5.5 | MEDIUM

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