CVE-2026-23644: esm-dev esm.sh Path Traversal

Vulnerability summary

CVE-2026-23644 is a high (CVSS 7.7) Path Traversal vulnerability in esm-dev esm.sh. EPSS estimates a 0.56% chance of exploitation in the next 30 days, higher than 45.4% of scored vulnerabilities. 1 public exploit is recorded.

Timeline

1. 18-01-2026
   PublishedVulnerability first disclosed.
2. 20-01-2026
   Last modifiedVulnerability information updated.

Description

esm.sh is a no-build content delivery network (CDN) for web development. Prior to Go pseeudoversion 0.0.0-20260116051925-c62ab83c589e, the software has a path traversal vulnerability due to an incomplete fix. `path.Clean` normalizes a path but does not prevent absolute paths in a malicious tar file. Commit https://github.com/esm-dev/esm.sh/commit/9d77b88c320733ff6689d938d85d246a3af9af16, corresponding to pseudoversion 0.0.0-20260116051925-c62ab83c589e, fixes this issue.

• CWE-22Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')The product uses external input to construct a pathname that is intended to identify a file or directory that is located underneath a restricted parent directory, but the product does not properly neutralize special elements within the pathname that can cause the pathname to resolve to a location that is outside of the restricted directory.