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HIGH

esm.sh: Legacy Route Path Traversal Can Lead to RCE

Published May 28, 2026

Description

esm.sh is a no-build content delivery network (CDN) for web development. In 137 and earlier, the legacy router first retrieves a response from legacyServer, parses the incoming request path, and ultimately writes the data to storage via buildStorage.Put. The router concatenates the path components without sanitizing them, producing a storage key. When this key is used, the underlying file system resolves the relative segments and writes the file to the specified path. Thus an attacker can craft a request that writes data to arbitrary locations on the server.

Affected products

Remediation

No remediation recorded yet.

Weaknesses (1)

References (5)

Change history (0)

No recorded changes yet.

Sources
CVE.org / MITRE
Status PUBLISHED
Assigner GitHub_M
Published May 28, 2026
Updated Jun 2, 2026
Reserved May 6, 2026
CISA Vulnrichment
Updated Jun 2, 2026
NVD
Status Deferred
Modified Jun 17, 2026
Red Hat
Severity n/a
Public date n/a
ENISA EUVD
Assigner GitHub_M
Published May 28, 2026
Updated Jun 2, 2026
Exploited since n/a
EUVD-2026-32910 GHSA-3636-H3VX-6465