{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-48126","assignerOrgId":"a0819718-46f1-4df5-94e2-005712e83aaa","state":"PUBLISHED","assignerShortName":"GitHub_M","dateReserved":"2026-05-20T18:46:58.291Z","datePublished":"2026-05-26T16:44:09.104Z","dateUpdated":"2026-05-26T17:27:56.507Z"},"containers":{"cna":{"title":"Algernon: Host header path traversal in --domain mode reads files and runs Lua from parent dir","problemTypes":[{"descriptions":[{"cweId":"CWE-22","lang":"en","description":"CWE-22: Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')","type":"CWE"}]},{"descriptions":[{"cweId":"CWE-23","lang":"en","description":"CWE-23: Relative Path Traversal","type":"CWE"}]},{"descriptions":[{"cweId":"CWE-644","lang":"en","description":"CWE-644: Improper Neutralization of HTTP Headers for Scripting Syntax","type":"CWE"}]}],"metrics":[{"cvssV3_1":{"attackComplexity":"LOW","attackVector":"NETWORK","availabilityImpact":"NONE","baseScore":8.2,"baseSeverity":"HIGH","confidentialityImpact":"HIGH","integrityImpact":"LOW","privilegesRequired":"NONE","scope":"UNCHANGED","userInteraction":"NONE","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:N","version":"3.1"}}],"references":[{"name":"https://github.com/xyproto/algernon/security/advisories/GHSA-jc3j-x6pg-4hmv","tags":["x_refsource_CONFIRM"],"url":"https://github.com/xyproto/algernon/security/advisories/GHSA-jc3j-x6pg-4hmv"}],"affected":[{"vendor":"xyproto","product":"algernon","versions":[{"version":"< 1.17.8","status":"affected"}]}],"providerMetadata":{"orgId":"a0819718-46f1-4df5-94e2-005712e83aaa","shortName":"GitHub_M","dateUpdated":"2026-05-26T16:44:09.104Z"},"descriptions":[{"lang":"en","value":"Algernon is a small self-contained pure-Go web server. Prior to 1.17.8, when algernon is started with --domain (or --letsencrypt, which silently turns on --domain at engine/flags.go:372), the request handler resolves the served directory by joining the configured --dir with the value of the client-supplied Host header. The join is performed by filepath.Join with no validation, so a Host: .. header walks one level above the document root. Subsequent file resolution then exposes everything in that parent directory — arbitrary file read, full directory listing, and, if any .lua file is present, server-side Lua execution. This vulnerability is fixed in 1.17.8."}],"source":{"advisory":"GHSA-jc3j-x6pg-4hmv","discovery":"UNKNOWN"}},"adp":[{"references":[{"url":"https://github.com/xyproto/algernon/security/advisories/GHSA-jc3j-x6pg-4hmv","tags":["exploit"]}],"metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-05-26T17:27:29.590530Z","id":"CVE-2026-48126","options":[{"Exploitation":"poc"},{"Automatable":"yes"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"title":"CISA ADP Vulnrichment","providerMetadata":{"orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","shortName":"CISA-ADP","dateUpdated":"2026-05-26T17:27:56.507Z"}}]}}