esm-dev esm.sh up to 137_6 Static File Server web/handler.go web.NewHandler path traversal

Summaryinfo

A vulnerability classified as problematic was found in esm-dev esm.sh up to 137_6. This vulnerability affects the function web.NewHandler of the file web/handler.go of the component Static File Server. The manipulation results in path traversal. This vulnerability was named CVE-2026-102657. The attack may be performed from remote. There is no available exploit. Upgrading the affected component is advised.

Detailsinfo

A vulnerability, which was classified as problematic, was found in esm-dev esm.sh up to 137_6. Affected is the function web.NewHandler of the file web/handler.go of the component Static File Server. The manipulation with an unknown input leads to a path traversal vulnerability. CWE is classifying the issue as CWE-22. 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. This is going to have an impact on confidentiality. CVE summarizes:

esm.sh is a no-build content delivery network (CDN) for web development. Prior to server version 137_7, the documented web.NewHandler static file server in web/handler.go joins the URL-decoded r.URL.Path with Config.AppDir without verifying that the result remains inside the configured application directory. URL-encoded dot segments such as %2e%2e bypass the plain traversal redirect performed by Go's ServeMux, allowing an unauthenticated remote attacker to make the server open and return files outside Config.AppDir that are readable by the server process. The confirmed impact is file disclosure only, and the issue is reachable with Dev disabled. This issue is fixed in server version 137_7.

The advisory is available at github.com. This vulnerability is traded as CVE-2026-102657 since 09/29/2026. The exploitability is told to be easy. It is possible to launch the attack remotely. The exploitation doesn't require any form of authentication. Technical details are known, but there is no available exploit. This vulnerability is assigned to T1006 by the MITRE ATT&CK project.

Upgrading to version 137_7 eliminates this vulnerability.

If you want to get best quality of vulnerability data, you may have to visit VulDB.

Productinfo

Vendor

• esm-dev

Name

• esm.sh

Version

• 137_6

Website

• Product: https://github.com/esm-dev/esm.sh/

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CPE 2.2info

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If you want to get best quality of vulnerability data, you may have to visit VulDB.

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