{"id":"CVE-2026-42091","aliases":["GHSA-rhf7-wvw3-vjvm","GO-2026-5625"],"url":"https://o3.security/vulnerability/CVE-2026-42091","summary":"goshs has Cross-Origin Arbitrary File Write via Missing CSRF on PUT and Wildcard CORS","details":"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.","published":"2026-05-04T17:24:47.890Z","modified":"2026-08-05T03:32:15.954066866Z","cvss":{"score":6.5,"severity":"MEDIUM","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N"},"epss":{"score":0.00165,"percentile":0.061,"asOf":"2026-08-08"},"cisaKev":null,"exploitsKnown":0,"affectedPackages":[{"ecosystem":"Go","name":"github.com/patrickhener/goshs/v2","fixedVersion":"2.0.2"},{"ecosystem":"Go","name":"github.com/patrickhener/goshs","fixedVersion":null}],"fix":{"url":"https://github.com/patrickhener/goshs/commit/0e715b94e10c3d1aa552276000f15f104dee2f32","label":"patrickhener/goshs@0e715b9"},"references":[{"type":"WEB","url":"https://github.com/patrickhener/goshs/releases/tag/v2.0.2"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/42xxx/CVE-2026-42091.json"},{"type":"ADVISORY","url":"https://github.com/patrickhener/goshs/security/advisories/GHSA-rhf7-wvw3-vjvm"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-42091"},{"type":"FIX","url":"https://github.com/patrickhener/goshs/commit/0e715b94e10c3d1aa552276000f15f104dee2f32"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-08-05T03:32:15.954066866Z"}}