GHSA-MP55-P8C9-RFW2

Vulnerability from github – Published: 2026-06-26 21:54 – Updated: 2026-06-26 21:54
VLAI
Summary
Hackney has CRLF / header injection via unvalidated `domain` and `path` options
Details

Summary

CRLF injection in hackney_cookie:setcookie/3 (src/hackney_cookie.erl). The function validates Name and Value against CR/LF and control characters but concatenates the domain and path options verbatim into the output binary. If either option carries attacker-controlled data, a Host header forwarded as the cookie domain, a request URI forwarded as the cookie path, a \r\n in the value splits the Set-Cookie header and lets the attacker inject additional headers into the HTTP response.

Details

1. Asymmetric validation

Lines 27–34 of hackney_cookie.erl run binary:match on Name and Value, rejecting =, ,, ;, whitespace, \r, \n, \013, and \014. The Domain and Path options (lines 47 and 51) skip this check entirely and land straight in the result iolist:

[<<"; Domain=">>, Domain]
[<<"; Path=">>,   Path]

iolist_to_binary(...) on line 63 flattens everything and returns it to the caller.

2. Injection

A Path of <<"/x\r\nSet-Cookie: admin=1; Path=/">> produces a binary with a literal \r\n. Written into a Set-Cookie response header, the receiving HTTP parser splits it into two headers — one legitimate, one attacker-controlled.

3. Realistic trigger

Common patterns: keying the cookie domain off Host, deriving the path from the request URI, or copying a Location path into a cookie. Any of these lets a remote attacker control the injected content.

PoC

  1. Call hackney_cookie:setcookie(<<"sid">>, <<"abc">>, [{path, <<"/x\r\nSet-Cookie: admin=1; Path=/">>}]).
  2. The returned binary contains a literal \r\n followed by a second Set-Cookie: line.
  3. Write the result into a Set-Cookie response header — the client parses two headers, including admin=1.

Impact

Cookie injection / HTTP response splitting at the hackney_cookie API boundary. Affects hackney 0.9.0 through 4.0.0 wherever domain or path options are populated from request data. Exploitation can overwrite session/auth cookies, fix cookies, or strip Secure/HttpOnly flags. CVSS v4.0: 2.1 (LOW) — requires attacker-controlled input to reach the domain or path option.

Resources

  • Introduction commit: https://github.com/benoitc/hackney/commit/602d5c7f2ea4acbc83ed75230655d935a0750ebc
  • Patch commit: https://github.com/benoitc/hackney/commit/8e02b99c28aea1b3fa2ddc0e66f51fe5bb0ac540
Severity
2.1 (Low)
CVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:L/SA:N
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{
  "affected": [
    {
      "package": {
        "ecosystem": "Hex",
        "name": "hackney"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0.9.0"
            },
            {
              "fixed": "4.0.1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-47069"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-93"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-06-26T21:54:19Z",
    "nvd_published_at": "2026-05-25T15:16:21Z",
    "severity": "LOW"
  },
  "details": "### Summary\n\nCRLF injection in `hackney_cookie:setcookie/3` (`src/hackney_cookie.erl`). The function validates `Name` and `Value` against CR/LF and control characters but concatenates the `domain` and `path` options verbatim into the output binary. If either option carries attacker-controlled data, a `Host` header forwarded as the cookie domain, a request URI forwarded as the cookie path, a `\\r\\n` in the value splits the `Set-Cookie` header and lets the attacker inject additional headers into the HTTP response.\n\n### Details\n\n**1. Asymmetric validation**\n\nLines 27\u201334 of `hackney_cookie.erl` run `binary:match` on `Name` and `Value`, rejecting `=`, `,`, `;`, whitespace, `\\r`, `\\n`, `\\013`, and `\\014`. The `Domain` and `Path` options (lines 47 and 51) skip this check entirely and land straight in the result iolist:\n\n```erlang\n[\u003c\u003c\"; Domain=\"\u003e\u003e, Domain]\n[\u003c\u003c\"; Path=\"\u003e\u003e,   Path]\n```\n\n`iolist_to_binary(...)` on line 63 flattens everything and returns it to the caller.\n\n**2. Injection**\n\nA `Path` of `\u003c\u003c\"/x\\r\\nSet-Cookie: admin=1; Path=/\"\u003e\u003e` produces a binary with a literal `\\r\\n`. Written into a `Set-Cookie` response header, the receiving HTTP parser splits it into two headers \u2014 one legitimate, one attacker-controlled.\n\n**3. Realistic trigger**\n\nCommon patterns: keying the cookie domain off `Host`, deriving the path from the request URI, or copying a `Location` path into a cookie. Any of these lets a remote attacker control the injected content.\n\n### PoC\n\n1. Call `hackney_cookie:setcookie(\u003c\u003c\"sid\"\u003e\u003e, \u003c\u003c\"abc\"\u003e\u003e, [{path, \u003c\u003c\"/x\\r\\nSet-Cookie: admin=1; Path=/\"\u003e\u003e}])`.\n2. The returned binary contains a literal `\\r\\n` followed by a second `Set-Cookie:` line.\n3. Write the result into a `Set-Cookie` response header \u2014 the client parses two headers, including `admin=1`.\n\n### Impact\n\nCookie injection / HTTP response splitting at the `hackney_cookie` API boundary. Affects hackney 0.9.0 through 4.0.0 wherever `domain` or `path` options are populated from request data. Exploitation can overwrite session/auth cookies, fix cookies, or strip `Secure`/`HttpOnly` flags. CVSS v4.0: **2.1 (LOW)** \u2014 requires attacker-controlled input to reach the `domain` or `path` option.\n\n## Resources\n\n* Introduction commit: https://github.com/benoitc/hackney/commit/602d5c7f2ea4acbc83ed75230655d935a0750ebc\n* Patch commit: https://github.com/benoitc/hackney/commit/8e02b99c28aea1b3fa2ddc0e66f51fe5bb0ac540",
  "id": "GHSA-mp55-p8c9-rfw2",
  "modified": "2026-06-26T21:54:19Z",
  "published": "2026-06-26T21:54:19Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/benoitc/hackney/security/advisories/GHSA-mp55-p8c9-rfw2"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-47069"
    },
    {
      "type": "WEB",
      "url": "https://github.com/benoitc/hackney/commit/8e02b99c28aea1b3fa2ddc0e66f51fe5bb0ac540"
    },
    {
      "type": "WEB",
      "url": "https://cna.erlef.org/cves/CVE-2026-47069.html"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/benoitc/hackney"
    },
    {
      "type": "WEB",
      "url": "https://osv.dev/vulnerability/EEF-CVE-2026-47069"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:L/SA:N",
      "type": "CVSS_V4"
    }
  ],
  "summary": "Hackney has CRLF / header injection via unvalidated `domain` and `path` options"
}


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Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

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