{"id":"CVE-2026-115700","aliases":["EEF-CVE-2026-115700","EUVD-2026-109834","GHSA-8c7g-m8h7-q24x"],"status":"published","title":"SSRF allowlist bypass via percent-encoded bracketed IPv6 or trailing-dot IP literal in hackney","description":"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%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.","severity":{"version":"4.0","score":6.9,"vector":"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","level":"medium","assessor":"cna","from":"cve"},"epss":{"day":"2026-11-12","score":0.00138,"percentile":0.03233,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":true},"cwes":["CWE-436","CWE-918"],"published":"2026-10-26T13:49:02Z","modified":"2026-11-04T02:30:32Z","fixes":[{"ecosystem":"Hex","package":"hackney","fixed_in":["4.9.0"],"sources":["osv"]}],"affected":[{"source":"osv","ecosystem":"Hex","package":"hackney","ranges":[{"type":"SEMVER","events":[{"introduced":"4.0.1"},{"fixed":"4.9.0"}]}],"versions":["4.0.1","4.0.2","4.0.3","4.1.0","4.2.0","4.2.1","4.2.2","4.2.3","4.3.0","4.4.0","4.4.1","4.4.2","4.4.3","4.4.5","4.5.0","4.5.1","4.5.2","4.6.0","4.6.1","4.7.0","4.7.1","4.7.2","4.7.3","4.7.4","4.8.0","4.8.1","4.8.2","4.8.3","4.8.4","4.8.5","4.8.6","4.8.7"]}],"products":[{"vendor":"benoitc","product":"hackney"},{"vendor":"hackney","product":"hackney"}],"references":[{"url":"https://github.com/benoitc/hackney/releases/tag/4.9.0","tags":["vendor-advisory","related","advisory"]},{"url":"https://cna.erlef.org/cves/CVE-2026-115700.html","tags":["related","web"]},{"url":"https://osv.dev/vulnerability/EEF-CVE-2026-115700","tags":["related","web"]},{"url":"https://github.com/benoitc/hackney/pull/987","tags":["related","fix","web"]},{"url":"https://github.com/benoitc/hackney/commit/452620a92ec1da2e6b4862a049a2a4f04b42068f","tags":["related","fix","web"]},{"url":"https://github.com/benoitc/hackney/commit/f19561a0b422376348c91537e51377ab7325f4ee","tags":["patch","fix"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-115700","tags":["advisory"]},{"url":"https://github.com/advisories/GHSA-8c7g-m8h7-q24x"},{"url":"https://github.com","tags":["web"]},{"url":"https://repo.hex.pm","tags":["web"]},{"url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/115xxx/CVE-2026-115700.json","tags":["advisory"]},{"url":"https://github.com/benoitc/hackney","tags":["package"]},{"url":"https://hex.pm/packages/hackney","tags":["package"]}],"sources":{"cve":[{"id":"CVE-2026-115700","title":"SSRF allowlist bypass via percent-encoded bracketed IPv6 or trailing-dot IP literal in hackney","description":"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%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.","status":"published","published":"2026-10-26T13:49:02.744Z","modified":"2026-11-02T21:10:51.594Z","cvss":[{"version":"4.0","score":6.9,"vector":"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","level":"medium","assessor":"cna"}],"cwes":["CWE-436","CWE-918"],"updated_at":"2026-11-03T00:01:30.510858Z"}],"euvd":[{"id":"EUVD-2026-109834","description":"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%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.","status":"published","published":"2026-10-26T13:49:02Z","modified":"2026-11-02T21:10:51Z","cvss":[{"version":"4.0","score":6.9,"vector":"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","level":"medium"}],"updated_at":"2026-11-03T05:08:36.865312Z"}],"ghsa":[{"id":"GHSA-8c7g-m8h7-q24x","title":"Interpretation Conflict vulnerability in hackney_url in benoitc hackney allows Server Side...","description":"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%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.","status":"published","published":"2026-10-26T15:34:43Z","modified":"2026-10-26T15:34:44Z","cvss":[{"version":"4.0","score":6.9,"vector":"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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X","level":"medium"}],"cwes":["CWE-436"],"updated_at":"2026-11-02T15:14:23.996006Z"}],"nvd":[{"id":"CVE-2026-115700","description":"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%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.","status":"published","published":"2026-10-26T14:16:32.08Z","modified":"2026-11-02T21:17:24.547Z","cvss":[{"version":"4.0","score":6.9,"vector":"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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X","level":"medium","assessor":"secondary"}],"cwes":["CWE-436","CWE-918"],"updated_at":"2026-11-03T00:02:35.749072Z"}],"osv":[{"id":"CVE-2026-115700","title":"SSRF allowlist bypass via percent-encoded bracketed IPv6 or trailing-dot IP literal in hackney","description":"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%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.","status":"published","published":"2026-10-26T13:49:02.744Z","modified":"2026-11-04T02:30:32.944260587Z","cvss":[{"version":"4.0","score":6.9,"vector":"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","level":"medium"}],"cwes":["CWE-436","CWE-918"],"updated_at":"2026-11-04T02:54:44.889498Z"},{"id":"EEF-CVE-2026-115700","title":"SSRF allowlist bypass via percent-encoded bracketed IPv6 or trailing-dot IP literal in hackney","description":"## Summary\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## Details\n\n**1. The gate.** `hackney_url:normalize/2` in `src/hackney_url.erl` percent-decodes a host that is not already an IP literal and raises `invalid_url_host` when `inet_parse:address/1` accepts the decoded value. This closed the plain percent-encoded IP case.\n\n**2. What the connect path accepts.** `hackney_happy:parse_address/1` removes a surrounding `[...]` pair before calling `inet:parse_address/1`, and the resolver treats a trailing dot as the root label. Neither form is accepted by `inet_parse:address/1`, so `[::ffff:127.0.0.1]` and `127.0.0.1.` pass the gate.\n\n**3. Result.** A percent-encoded bracketed IPv6 literal such as `%5B%3A%3Affff%3A127%2E0%2E0%2E1%5D`, or an IPv4 literal with a trailing dot, is not an IP address to a caller's check based on `uri_string:parse/1` and `inet:parse_address/1`, but hackney connects to the address it denotes. The same applies to a `Location` target when redirects are followed. The fix strips one bracket pair and one trailing dot in `ip_candidate/1` before the gate.\n\n## Impact\n\nAn application that checks user-supplied URLs against an IP allowlist before handing them to hackney can be made to request loopback, link-local metadata and private-network addresses that the allowlist rejects when they are written plainly.\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.\n\n## Configurations\n\nThe application passes URLs that an untrusted party can influence to hackney and relies on its own host allowlist, built on `uri_string:parse/1` or `inet:parse_address/1`, to keep requests away from internal addresses.","status":"published","published":"2026-10-26T13:49:02.744Z","modified":"2026-10-26T14:00:04.842678043Z","cvss":[{"version":"4.0","score":6.9,"vector":"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","level":"medium"}],"cwes":["CWE-436","CWE-918"],"updated_at":"2026-11-02T15:46:33.047032Z"}]}}