CVE-2026-102657
HIGH
MEDIUM
Priority: 0.05
BB Relevance:
75/100
Published: 2026-11-06
Modified: 2026-11-11
First seen: 2026-11-06
Status: active
Attack Surface
Network
Low Complexity
No Auth
No Interaction
Conf. Impact
CVSS Vector Breakdown
AV:
Network
AC:
Low
PR:
None
UI:
None
S:
Unchanged
C:
High
I:
None
A:
None
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.
Weakness Classification (1)
References & Advisories (5)
x_refsource_MISC
x_refsource_MISC
x_refsource_MISC
x_refsource_MISC
x_refsource_CONFIRM