CVE-2026-44593

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

Published May 28, 2026 CVSS 4.0 · 8.7 High EPSS < 1% KEV · Not listed
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.

Remediation

No solution or workaround provided in the CVE record

Tracking

Sign in to view the affected projects.

Advisories

Source ID Title
Github GHSA Github GHSA GHSA-3636-h3vx-6465 esm.sh: Legacy Route Path Traversal Can Lead to RCE
History
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'poc', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Type Values Removed Values Added
First Time appeared Esm-dev
Esm-dev esmsh
Vendors & Products Esm-dev
Esm-dev esmsh
Type Values Removed Values Added
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.
Title esm.sh: Legacy Route Path Traversal Can Lead to RCE
Weaknesses CWE-22
References
Metrics cvssV4_0

{'score': 8.7, 'vector': 'CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
GitHub_M
Published
Updated
Jun 2, 2026, 3:01 PM
Reserved
May 6, 2026, 9:49 PM
Status
Deferred
Published
May 28, 2026, 4:16 PM
Modified
Oct 26, 2026, 11:10 AM