{
  "schema_version": "1.5.0",
  "id": "CURL-CVE-2026-86409",
  "aliases": [
    "CVE-2026-86409"
  ],
  "summary": "stale SigV4 headers sent unintended",
  "modified": "2026-09-17T12:57:32.00Z",
  "database_specific": {
    "package": "curl",
    "affects": "lib",
    "URL": "https://curl.se/docs/CVE-2026-86409.json",
    "www": "https://curl.se/docs/CVE-2026-86409.html",
    "issue": "https://hackerone.com/reports/3973135",
    "CWE": {
      "id": "CWE-201",
      "desc": "Information Exposure Through Sent Data"
    },
    "last_affected": "8.21.0",
    "severity": "Low"
  },
  "published": "2026-10-14T08:00:00.00Z",
  "affected": [
    {
      "ranges": [
        {
           "type": "SEMVER",
           "events": [
             {"introduced": "7.75.0"},
             {"fixed": "8.14.3"},
             {"introduced": "8.15.0"},
             {"fixed": "8.16.2"},
             {"introduced": "8.17.0"},
             {"fixed": "8.20.2"},
             {"introduced": "8.21.0"},
             {"fixed": "8.22.0"}
           ]
        },
        {
           "type": "GIT",
           "repo": "https://github.com/curl/curl.git",
           "events": [
             {"introduced": "08e8455dddc5e48e58a12ade3815c01ae3da3b64"},
             {"fixed": "c3c70440e8d9938c0bb732595751e8aebc614f24"}
           ]
        }
      ],
      "versions": [
        "8.21.0", "8.20.0", "8.19.0", "8.18.0", "8.17.0", "8.16.0", "8.15.0", 
        "8.14.1", "8.14.0", "8.13.0", "8.12.1", "8.12.0", "8.11.1", "8.11.0", 
        "8.10.1", "8.10.0", "8.9.1", "8.9.0", "8.8.0", "8.7.1", "8.7.0", 
        "8.6.0", "8.5.0", "8.4.0", "8.3.0", "8.2.1", "8.2.0", "8.1.2", 
        "8.1.1", "8.1.0", "8.0.1", "8.0.0", "7.88.1", "7.88.0", "7.87.0", 
        "7.86.0", "7.85.0", "7.84.0", "7.83.1", "7.83.0", "7.82.0", "7.81.0", 
        "7.80.0", "7.79.1", "7.79.0", "7.78.0", "7.77.0", "7.76.1", "7.76.0", 
        "7.75.0"
      ]
    }
  ],
  "credits": [
    {
      "name": "Stanislav Fort (Aisle Research)",
      "type": "FINDER"
    },
    {
      "name": "Viktor Szakats",
      "type": "REMEDIATION_DEVELOPER"
    }
  ],
  "details": "Setting `CURLOPT_AWS_SIGV4` to NULL but does not disable SigV4 authentication,\ncontrary to expectations and documentation. A subsequent transfer on the same\nhandle still sends an `Authorization: AWS4-HMAC-SHA256` header to whatever URL\nis set next, leaking state information."
}