CVE-2026-102657
esm.sh is a no-build content delivery network (CDN) for web development
- Risk score
- 50/100
- CVSS
- 7.5 v3.1
- Published
- 6 Nov 2026
Open in the live forecast Today's forecast
What to know
- What it is
- 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-encod…
- Affected
- See advisory
- Fix
- Apply the vendor's security update; see the linked advisory.
- Exploitation
- No known exploitation
Why it is Yellow
- CVSS 7.5 high
- Remotely exploitable without logging in
References
- https://github.com/esm-dev/esm.sh/commit/468b6b2a4b4dfec334cf6b33b01fcd4e5cd93bed
- https://github.com/esm-dev/esm.sh/commit/fc3b345e73aeaa0b7a05b6f27d91c05fdf5f9b53
- https://github.com/esm-dev/esm.sh/pull/1376
- https://github.com/esm-dev/esm.sh/releases/tag/v137_7
- https://github.com/esm-dev/esm.sh/security/advisories/GHSA-g3c2-rjq2-c763
Original 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.
Last activity 6 Nov 2026. Patch Forecast updates every hour.