CVE-2026-42091: Goshs

Medium severity, CVSS 6.5. EPSS: 0.2% chance of exploitation in the next 30 days.

goshs is a SimpleHTTPServer written in Go. Prior to version 2.0.2, the PUT upload handler (httpserver/updown.go) lacks the CSRF token validation that was added to the POST upload handler during the CVE-2026-40883 fix. Combined with the unconditional Access-Control-Allow-Origin: * on the OPTIONS preflight handler (httpserver/server.go), any website can write arbitrary files to a goshs instance through the victim's browser — bypassing network isolation (e.g. localhost, internal network). This issue has been patched in version 2.0.2.

Affected products

• Goshs Goshs: before 2.0.2 (fixed in 2.0.2)

Published 2026-05-04. Last modified 2026-06-17.