{"id":"CVE-2026-115700","title":"SSRF allowlist bypass via percent-encoded bracketed IPv6 or trailing-dot IP literal in hackney","summary":"Interpretation Conflict vulnerability in hackney_url in benoitc hackney allows Server Side Request Forgery via a percent-encoded bracketed IPv6 literal or an IP literal with a trailing dot. A host such as %5B%3A%3Affff%3A127%2E0%2E0%2E1%…","severity":"medium","cvss":6.9,"cvssVector":"CVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:N/VC:H/VI:N/VA:N/SC:H/SI:N/SA:N","cvssSource":"cna","cwe":["CWE-436","CWE-918"],"vendor":"benoitc","product":"hackney","affected":["hackney >= 4.0.1 < 4.9.0","benoitc/hackney >= 452620a92ec1da2e6b4862a049a2a4f04b42068f < f19561a0b422376348c91537e51377ab7325f4ee"],"published":"2026-10-26","updated":"2026-10-26","sourceUpdated":"2026-10-26T13:49:02.744Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-115700","references":[{"url":"https://github.com/benoitc/hackney/releases/tag/4.9.0","label":"hackney 4.9.0 release notes"},{"url":"https://cna.erlef.org/cves/CVE-2026-115700.html","label":"EEF CNA record for CVE-2026-115700"},{"url":"https://osv.dev/vulnerability/EEF-CVE-2026-115700","label":"OSV record EEF-CVE-2026-115700"},{"url":"https://github.com/benoitc/hackney/pull/987","label":"Refuse bracketed and trailing-dot IP literals in normalize/2 (benoitc/hackney#987)"},{"url":"https://github.com/benoitc/hackney/commit/452620a92ec1da2e6b4862a049a2a4f04b42068f","label":"Introducing commit 452620a in benoitc/hackney"},{"url":"https://github.com/benoitc/hackney/commit/f19561a0b422376348c91537e51377ab7325f4ee","label":"Fix commit f19561a in benoitc/hackney"}],"tags":["cve.org"],"ingestedAt":"2026-10-26T14:27:31.814Z","slug":"CVE-2026-115700","body":"## Overview\n\nInterpretation Conflict vulnerability in hackney_url in benoitc hackney allows Server Side Request Forgery via a percent-encoded bracketed IPv6 literal or an IP literal with a trailing dot. A host such as %5B%3A%3Affff%3A127%2E0%2E0%2E1%5D (decoding to [::ffff:127.0.0.1]) or 127.0.0.1. is not an IP address to a caller's allowlist built on uri_string:parse/1 and inet:parse_address/1, while hackney connects to the address it denotes. The same applies to a Location target when redirects are followed.\n\nThe IP-literal gate that hackney_url:normalize/2 applies to a percent-decoded host, added to close the percent-encoded IP bypass of CVE-2026-47076, passes the decoded value to inet_parse:address/1 as is. The connect path in hackney_happy:parse_address/1 drops a surrounding bracket pair, and the resolver ignores a trailing dot, so both forms pass the gate and still reach the literal address. Domain names with a trailing dot and unencoded IPv6 literals are not affected.\n\nThis issue affects hackney: from 4.0.1 before 4.9.0.\n\n## Affected\n\n- `hackney >= 4.0.1 < 4.9.0`\n- `benoitc/hackney >= 452620a92ec1da2e6b4862a049a2a4f04b42068f < f19561a0b422376348c91537e51377ab7325f4ee`\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.\n\n### Workarounds\n\nRun the allowlist on the host that hackney_url:normalize/1 returns for the parsed URL, and strip a surrounding bracket pair and a trailing dot from it before the IP check, so the check sees the same address the connect path uses.","depth":"sunlit","depthScore":38,"depthScoreParts":{"impact":38,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}