{"id":"CVE-2026-66064","aliases":["GHSA-964w-f6gj-5236"],"title":"goshs has ACL Bypass & Path Traversal","summary":"goshs has ACL Bypass & Path Traversal","severity":"medium","cvss":5.3,"cwe":["CWE-22","CWE-41","CWE-863"],"vendor":"patrickhener","product":"github.com/patrickhener/goshs/v2","ecosystem":"go","affected":["github.com/patrickhener/goshs/v2 <= 2.1.4","goshs.de/goshs/v2 <= 2.1.4","github.com/patrickhener/goshs <= 1.1.4","goshs.de/goshs <= 1.1.4"],"patched":["github.com/patrickhener/goshs/v2 2.1.5-0.20260727065949-f3ef599e4091","goshs.de/goshs/v2 2.1.5-0.20260727065949-f3ef599e4091"],"published":"2026-07-28","updated":"2026-07-28","source":"GHSA","sourceUrl":"https://github.com/advisories/GHSA-964w-f6gj-5236","references":[{"url":"https://github.com/goshs-labs/goshs/security/advisories/GHSA-964w-f6gj-5236"},{"url":"https://github.com/goshs-labs/goshs/pull/222"},{"url":"https://github.com/goshs-labs/goshs/commit/f3ef599e409151d1380866e47de8b1afb0bb54fa"},{"url":"https://github.com/advisories/GHSA-964w-f6gj-5236"}],"tags":["ghsa","go"],"ingestedAt":"2026-07-28T22:40:03.038Z","epss":0.00308,"epssPercentile":0.2381,"slug":"CVE-2026-66064","body":"## Overview\n\n## Summary\n\n`sendFile` derives the served filename from the raw request path while opening the file from the cleaned path, so appending a trailing slash empties the derived name and defeats both the never-serve rule for the ACL file and the block list. \n\n## Finding (Medium): trailing-slash ACL and hidden-file bypass\n\nhttpserver/handler.go, sendFile (lines 789-801) takes the filename from the RAW req.URL.Path while the file itself is opened from the filepath.Clean-ed path. The two disagree, and a trailing slash makes the derived name the empty string. Both protections key on that derived name, so both are defeated: the rule that never serves the .goshs ACL file, and the acl.Block list.\n\nMeasured, with negative controls:\n\n```\nGET /blocked/secret.txt    -> 404          (control, correctly blocked)\nGET /blocked/secret.txt/   -> 200 + contents\nGET /blocked/.goshs/       -> 200, returns the ACL file itself,\n                              including the admin:$2a$... bcrypt hash\n```\n\nUnauthenticated when the ACL is configured block-only (common usage). Stated precisely: AUTHENTICATION IS NOT BYPASSED. An unauthenticated request against a directory protected by authentication still returns 401 under the same trick; I tested that. The claim is specifically that the block list and the ACL-file protection are bypassed. In-tree evidence that sendFile is the defect: the sibling handlers doDir and bulkDownload both derive the name correctly; sendFile is the lone outlier.\n\n## Suggested fixes\n\n1. Derive the served filename from the same cleaned path used to open the file, so the authorization decision and the file access cannot disagree.\n\n## Tooling\n\nAI assistance was used while investigating. The finding was reproduced against a running server on loopback with negative controls, including the 404-versus-200 pair and the authenticated-directory control that shows authentication is not affected.\n\n## Affected packages\n\n- `github.com/patrickhener/goshs/v2 <= 2.1.4`\n- `goshs.de/goshs/v2 <= 2.1.4`\n- `github.com/patrickhener/goshs <= 1.1.4`\n- `goshs.de/goshs <= 1.1.4`\n\n## Remediation\n\nUpgrade to a patched release:\n\n- `github.com/patrickhener/goshs/v2 2.1.5-0.20260727065949-f3ef599e4091`\n- `goshs.de/goshs/v2 2.1.5-0.20260727065949-f3ef599e4091`","depth":"sunlit","depthScore":29,"depthScoreParts":{"impact":29.2,"likelihood":0.1,"exploitation":0,"ransomware":0},"changes":[]}