CVE-2026-86411 (GCVE-0-2026-86411)
Vulnerability from cvelistv5
Published
2026-10-20 20:02
Modified
2026-10-20 20:02
Severity ?
CWE
Summary
An `ftp://` transfer configured with `CURLUSESSL_NONE` can reuse a pooled FTP control connection that a previous easy handle upgraded with `STARTTLS` and authenticated using a client certificate. The second handle performs neither a new TLS handshake nor a new FTP login, so the server continues to authorize it under the first handle's certificate identity.
References
Impacted products
Vendor Product Version
curl curl Version: 8.21.0   ≤ 8.21.0
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "curl",
          "vendor": "curl",
          "versions": [
            {
              "lessThanOrEqual": "8.21.0",
              "status": "affected",
              "version": "8.21.0",
              "versionType": "semver"
            }
          ]
        }
      ],
      "credits": [
        {
          "lang": "en",
          "type": "finder",
          "value": "Stanislav Fort (Aisle Research)"
        },
        {
          "lang": "en",
          "type": "remediation developer",
          "value": "Stefan Eissing"
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "An `ftp://` transfer configured with `CURLUSESSL_NONE` can reuse a pooled FTP\ncontrol connection that a previous easy handle upgraded with `STARTTLS` and\nauthenticated using a client certificate. The second handle performs neither a\nnew TLS handshake nor a new FTP login, so the server continues to authorize it\nunder the first handle\u0027s certificate identity."
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "description": "CWE-488 Exposure of Data Element to Wrong Session",
              "lang": "en"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-10-20T20:02:03.431Z",
        "orgId": "2499f714-1537-4658-8207-48ae4bb9eae9",
        "shortName": "curl"
      },
      "references": [
        {
          "name": "json",
          "url": "https://curl.se/docs/CVE-2026-86411.json"
        },
        {
          "name": "www",
          "url": "https://curl.se/docs/CVE-2026-86411.html"
        },
        {
          "name": "issue",
          "url": "https://hackerone.com/reports/3973190"
        }
      ],
      "title": "FTP connection reuse inherits client-certificate"
    }
  },
  "cveMetadata": {
    "assignerOrgId": "2499f714-1537-4658-8207-48ae4bb9eae9",
    "assignerShortName": "curl",
    "cveId": "CVE-2026-86411",
    "datePublished": "2026-10-20T20:02:03.431Z",
    "dateReserved": "2026-09-07T12:11:48.560Z",
    "dateUpdated": "2026-10-20T20:02:03.431Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


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