{
  "schema_version": "1.5.0",
  "id": "CURL-CVE-2026-5545",
  "aliases": [
    "CVE-2026-5545"
  ],
  "summary": "wrong reuse of HTTP Negotiate connection",
  "modified": "2026-04-29T07:48:41.00Z",
  "database_specific": {
    "package": "curl",
    "affects": "both",
    "URL": "https://curl.se/docs/CVE-2026-5545.json",
    "www": "https://curl.se/docs/CVE-2026-5545.html",
    "issue": "https://hackerone.com/reports/3642555",
    "CWE": {
      "id": "CWE-305",
      "desc": "Authentication Bypass by Primary Weakness"
    },
    "last_affected": "8.19.0",
    "severity": "Medium"
  },
  "published": "2026-04-29T08:00:00.00Z",
  "affected": [
    {
      "ranges": [
        {
           "type": "SEMVER",
           "events": [
             {"introduced": "7.10.6"},
             {"fixed": "8.20.0"}
           ]
        },
        {
           "type": "GIT",
           "repo": "https://github.com/curl/curl.git",
           "events": [
             {"introduced": "e56ae1426cb7a0a4a427cf8d6099a821fdaae428"},
             {"fixed": "33e43985b8f3b9e66691d06e70be0395849856cd"}
           ]
        }
      ],
      "versions": [
        "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", "7.74.0", 
        "7.73.0", "7.72.0", "7.71.1", "7.71.0", "7.70.0", "7.69.1", "7.69.0", 
        "7.68.0", "7.67.0", "7.66.0", "7.65.3", "7.65.2", "7.65.1", "7.65.0", 
        "7.64.1", "7.64.0", "7.63.0", "7.62.0", "7.61.1", "7.61.0", "7.60.0", 
        "7.59.0", "7.58.0", "7.57.0", "7.56.1", "7.56.0", "7.55.1", "7.55.0", 
        "7.54.1", "7.54.0", "7.53.1", "7.53.0", "7.52.1", "7.52.0", "7.51.0", 
        "7.50.3", "7.50.2", "7.50.1", "7.50.0", "7.49.1", "7.49.0", "7.48.0", 
        "7.47.1", "7.47.0", "7.46.0", "7.45.0", "7.44.0", "7.43.0", "7.42.1", 
        "7.42.0", "7.41.0", "7.40.0", "7.39.0", "7.38.0", "7.37.1", "7.37.0", 
        "7.36.0", "7.35.0", "7.34.0", "7.33.0", "7.32.0", "7.31.0", "7.30.0", 
        "7.29.0", "7.28.1", "7.28.0", "7.27.0", "7.26.0", "7.25.0", "7.24.0", 
        "7.23.1", "7.23.0", "7.22.0", "7.21.7", "7.21.6", "7.21.5", "7.21.4", 
        "7.21.3", "7.21.2", "7.21.1", "7.21.0", "7.20.1", "7.20.0", "7.19.7", 
        "7.19.6", "7.19.5", "7.19.4", "7.19.3", "7.19.2", "7.19.1", "7.19.0", 
        "7.18.2", "7.18.1", "7.18.0", "7.17.1", "7.17.0", "7.16.4", "7.16.3", 
        "7.16.2", "7.16.1", "7.16.0", "7.15.5", "7.15.4", "7.15.3", "7.15.2", 
        "7.15.1", "7.15.0", "7.14.1", "7.14.0", "7.13.2", "7.13.1", "7.13.0", 
        "7.12.3", "7.12.2", "7.12.1", "7.12.0", "7.11.2", "7.11.1", "7.11.0", 
        "7.10.8", "7.10.7", "7.10.6"
      ]
    }
  ],
  "credits": [
    {
      "name": "Quac Tran and Ngoc Hieu",
      "type": "FINDER"
    },
    {
      "name": "Stefan Eissing",
      "type": "REMEDIATION_DEVELOPER"
    }
  ],
  "details": "libcurl might in some circumstances reuse the wrong connection when asked to\ndo an authenticated HTTP(S) request after a Negotiate-authenticated one, when\nboth use the same host.\n\nlibcurl features a pool of recent connections so that subsequent requests can\nreuse an existing connection to avoid overhead.\n\nWhen reusing a connection a range of criteria must be met. Due to a logical\nerror in the code, a request that was issued by an application could\nwrongfully reuse an existing connection to the same server that was\nauthenticated using different credentials.\n\nAn application that first uses Negotiate authentication to a server with\n`user1:password1` and then does another operation to the same server asking\nfor any authentication method but for `user2:password2` (while the previous\nconnection is still alive) - the second request gets confused and wrongly\nreuses the same connection and sends the new request over that connection\nthinking it uses a mix of user1's and user2's credentials when it is in fact\nstill using the connection authenticated for user1..."
}