CVE-2026-44593

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.

CVSS 4.0

8.7CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N

EPSS

0.4% chance of exploitation in the next 30 days; higher than 29% of CVEs (scores of 2026-10-25)

CWE

CWE-22

Published

2026-05-28

Modified

2026-10-26

Record from

the NVD, synced 2026-10-26

Packages (OSV)

References

• https://github.com/esm-dev/esm.sh/security/advisories/GHSA-3636-h3vx-6465
• https://github.com/esm-dev/esm.sh/security/advisories/GHSA-3636-h3vx-6465

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