CVE-2026-44593

What it is

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.

At a glance

Exploitability

Can be exploited over the network without logging in. High risk of data tampering.

Exploit odds

0.4% chance of exploitation in the next 30 days (EPSS).

Fix

A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

1. 2026-05-28 16:16 UTC PublishedDisclosed publicly on CVE.org and NVD
2. 2026-10-26 11:10 UTC Last updatedMost recent change to the record

Details

Published

2026-05-28 16:16 UTC

Last modified

2026-10-26 11:10 UTC

Exploit probability

0.4% · EPSS, next 30 days

Weakness

CWE-22 · Path traversal

Record status

Deferred

Attack profile CVSS 4.0 · 8.7

Attack vector

Network

Complexity

Low

Attack requirements

None

Privileges needed

None

User interaction

None

Confidentiality

None

Integrity

High

Availability

None