{"id":"CVE-2026-47076","aliases":["EEF-CVE-2026-47076","GHSA-pj7v-xfvx-wmjq"],"url":"https://o3.security/vulnerability/CVE-2026-47076","summary":"SSRF allowlist bypass via percent-encoded host in hackney","details":"Interpretation Conflict vulnerability in benoitc hackney allows Server Side Request Forgery. hackney_url:normalize/2 URL-decodes the host component after the URL has been parsed into a #hackney_url{} record. OTP's uri_string:parse/1 and inet:parse_address/1 do not decode percent-escapes in the host, so a URL such as http://%31%32%37%2E%30%2E%30%2E%31/ is seen by a caller's allowlist validator with host %31%32%37%2E%30%2E%30%2E%31 (not an IP address), which passes the allowlist check. hackney's normalizer then decodes the host to 127.0.0.1 and opens a TCP connection to loopback. Because hackney:request/5 always calls hackney_url:normalize/2 with no opt-out, every request that takes a binary or list URL is affected. The same technique reaches cloud instance metadata services (169.254.169.254), RFC1918 networks, and any admin interface listening on localhost.\n\nThis issue affects hackney: from 0.13.0 before 4.0.1.","published":"2026-05-25T14:00:46.707Z","modified":"2026-08-12T03:51:22.046833979Z","cvss":null,"epss":{"score":0.00229,"percentile":0.13601,"asOf":"2026-09-07"},"cisaKev":null,"exploitsKnown":0,"affectedPackages":[{"ecosystem":"Hex","name":"hackney","fixedVersion":"4.0.1"}],"fix":{"url":"https://github.com/benoitc/hackney/commit/452620a92ec1da2e6b4862a049a2a4f04b42068f","label":"benoitc/hackney@452620a"},"references":[{"type":"WEB","url":"https://cna.erlef.org/cves/CVE-2026-47076.html"},{"type":"WEB","url":"https://github.com"},{"type":"WEB","url":"https://osv.dev/vulnerability/EEF-CVE-2026-47076"},{"type":"WEB","url":"https://repo.hex.pm"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/47xxx/CVE-2026-47076.json"},{"type":"ADVISORY","url":"https://github.com/benoitc/hackney/security/advisories/GHSA-pj7v-xfvx-wmjq"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-47076"},{"type":"FIX","url":"https://github.com/benoitc/hackney/commit/452620a92ec1da2e6b4862a049a2a4f04b42068f"},{"type":"PACKAGE","url":"https://github.com/benoitc/hackney"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-08-12T03:51:22.046833979Z"}}