CVE-2026-42091
CWE-352Published: May 4, 2026· Updated: May 7, 2026
Official Description
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.
Technical Analysis
CVE-2026-42091 can be exploited remotely over the network without requiring physical or adjacent access, significantly expanding the attack surface for threat actors.
Exploitation does not require any privileges, though user interaction (Required) is needed, which slightly reduces the risk of mass automated attacks.
A successful exploit results in full integrity compromise (data manipulation), with a CVSS base score of 6.5.
CVSS v3.1 Vector Breakdown
Affected Vendors & Products
Exploit & PoC Resources
All References (4)
Quick Facts
Related CVEs (CWE-352)
Recommended Actions
- →Apply vendor patches immediately
- →Monitor CVE-2026-42091 in threat intel feeds
- →Review IDS/IPS signatures for exploitation attempts