CSRF in Goshs
CVE-2026-42091
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.
Vulnerability class: CSRF (Cross-Site Request Forgery)
Published · last modified .
CVSS v3 metric
CVSS v3 base score 6.5 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N.
EPSS exploit prediction
EPSS: 0.002 (12.0th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 12th percentile — 12.0% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.002 · newest: 0.002 · change: +0.001
Affected products
- Goshs
- Patrickhener Goshs — versions < 2.0.2
Weakness classification (CWE)
References
- github.com/patrickhener/goshs/security/advisories/GHSA-rhf7-wvw3-vjvm (Exploit, Vendor Advisory)
- github.com/patrickhener/goshs/commit/0e715b94e10c3d1aa552276000f15f104dee2f32 (Patch)
- github.com/patrickhener/goshs/releases/tag/v2.0.2 (Product, Release Notes)
Frequently asked questions
- What is CVE-2026-42091?
- CVE-2026-42091 is a medium-severity vulnerability in Goshs, classified under Cross-Site Request Forgery (CSRF). CVSS score: 6.5/10. Published 2026-05-04.
- How severe is CVE-2026-42091?
- Medium severity. CVSS v3 base score is 6.5 out of 10.