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.
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History
Fri, 06 Nov 2026 21:00:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Description | 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. | |
| Title | esm.sh: web.NewHandler allows arbitrary file read via encoded dot-segment path traversal | |
| Weaknesses | CWE-22 | |
| References |
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| Metrics |
cvssV3_1
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Status: PUBLISHED
Assigner: GitHub_M
Published:
Updated: 2026-11-06T20:49:28.708Z
Reserved: 2026-09-29T15:56:02.101Z
Link: CVE-2026-102657
No data.
Status : Deferred
Published: 2026-11-06T21:17:05.863
Modified: 2026-11-06T21:17:06.027
Link: CVE-2026-102657
No data.
OpenCVE Enrichment
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Weaknesses