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FKIE_CVE-2026-9547

Vulnerability from fkie_nvd - Published: 2026-07-03 07:16 - Updated: 2026-09-15 07:16
Summary
When a libcurl-based application performs transfers via `SCP://` or `SFTP://` and utilizes the `CURLOPT_SSH_KEYFUNCTION` callback, it may silently accept an untrusted server. This vulnerability occurs when a server presents a host key type that does not match the specific key type already recorded for that host in the `known_hosts` file. Instead of rejecting the mismatch, the callback mechanism fails to properly enforce the restriction, allowing the connection to succeed without warning and risking a potential man-in-the-middle attack.
Impacted products
Vendor Product Version
haxx curl *

{
  "affected": [
    {
      "affectedData": [
        {
          "defaultStatus": "unaffected",
          "product": "curl",
          "vendor": "curl",
          "versions": [
            {
              "lessThan": "8.14.2",
              "status": "affected",
              "version": "7.69.0",
              "versionType": "semver"
            },
            {
              "lessThan": "8.16.1",
              "status": "affected",
              "version": "8.15.0",
              "versionType": "semver"
            },
            {
              "lessThan": "8.20.1",
              "status": "affected",
              "version": "8.17.0",
              "versionType": "semver"
            }
          ]
        },
        {
          "defaultStatus": "unaffected",
          "product": "curl",
          "repo": "https://github.com/curl/curl.git",
          "vendor": "curl",
          "versions": [
            {
              "lessThan": "0b8dbbc63c98777e4584cb9fbd71df3464008ad1",
              "status": "affected",
              "version": "507cf6a13db0375eadd4655b4c64710db29e9cf2",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "unaffected",
          "product": "curl",
          "vendor": "curl",
          "versions": [
            {
              "status": "affected",
              "version": "8.20.0"
            },
            {
              "status": "affected",
              "version": "8.19.0"
            },
            {
              "status": "affected",
              "version": "8.18.0"
            },
            {
              "status": "affected",
              "version": "8.17.0"
            },
            {
              "status": "affected",
              "version": "8.16.0"
            },
            {
              "status": "affected",
              "version": "8.15.0"
            },
            {
              "status": "affected",
              "version": "8.14.1"
            },
            {
              "status": "affected",
              "version": "8.14.0"
            },
            {
              "status": "affected",
              "version": "8.13.0"
            },
            {
              "status": "affected",
              "version": "8.12.1"
            },
            {
              "status": "affected",
              "version": "8.12.0"
            },
            {
              "status": "affected",
              "version": "8.11.1"
            },
            {
              "status": "affected",
              "version": "8.11.0"
            },
            {
              "status": "affected",
              "version": "8.10.1"
            },
            {
              "status": "affected",
              "version": "8.10.0"
            },
            {
              "status": "affected",
              "version": "8.9.1"
            },
            {
              "status": "affected",
              "version": "8.9.0"
            },
            {
              "status": "affected",
              "version": "8.8.0"
            },
            {
              "status": "affected",
              "version": "8.7.1"
            },
            {
              "status": "affected",
              "version": "8.7.0"
            },
            {
              "status": "affected",
              "version": "8.6.0"
            },
            {
              "status": "affected",
              "version": "8.5.0"
            },
            {
              "status": "affected",
              "version": "8.4.0"
            },
            {
              "status": "affected",
              "version": "8.3.0"
            },
            {
              "status": "affected",
              "version": "8.2.1"
            },
            {
              "status": "affected",
              "version": "8.2.0"
            },
            {
              "status": "affected",
              "version": "8.1.2"
            },
            {
              "status": "affected",
              "version": "8.1.1"
            },
            {
              "status": "affected",
              "version": "8.1.0"
            },
            {
              "status": "affected",
              "version": "8.0.1"
            },
            {
              "status": "affected",
              "version": "8.0.0"
            },
            {
              "status": "affected",
              "version": "7.88.1"
            },
            {
              "status": "affected",
              "version": "7.88.0"
            },
            {
              "status": "affected",
              "version": "7.87.0"
            },
            {
              "status": "affected",
              "version": "7.86.0"
            },
            {
              "status": "affected",
              "version": "7.85.0"
            },
            {
              "status": "affected",
              "version": "7.84.0"
            },
            {
              "status": "affected",
              "version": "7.83.1"
            },
            {
              "status": "affected",
              "version": "7.83.0"
            },
            {
              "status": "affected",
              "version": "7.82.0"
            },
            {
              "status": "affected",
              "version": "7.81.0"
            },
            {
              "status": "affected",
              "version": "7.80.0"
            },
            {
              "status": "affected",
              "version": "7.79.1"
            },
            {
              "status": "affected",
              "version": "7.79.0"
            },
            {
              "status": "affected",
              "version": "7.78.0"
            },
            {
              "status": "affected",
              "version": "7.77.0"
            },
            {
              "status": "affected",
              "version": "7.76.1"
            },
            {
              "status": "affected",
              "version": "7.76.0"
            },
            {
              "status": "affected",
              "version": "7.75.0"
            },
            {
              "status": "affected",
              "version": "7.74.0"
            },
            {
              "status": "affected",
              "version": "7.73.0"
            },
            {
              "status": "affected",
              "version": "7.72.0"
            },
            {
              "status": "affected",
              "version": "7.71.1"
            },
            {
              "status": "affected",
              "version": "7.71.0"
            },
            {
              "status": "affected",
              "version": "7.70.0"
            },
            {
              "status": "affected",
              "version": "7.69.1"
            },
            {
              "status": "affected",
              "version": "7.69.0"
            }
          ]
        }
      ],
      "source": "2499f714-1537-4658-8207-48ae4bb9eae9"
    }
  ],
  "configurations": [
    {
      "nodes": [
        {
          "cpeMatch": [
            {
              "criteria": "cpe:2.3:a:haxx:curl:*:*:*:*:*:*:*:*",
              "matchCriteriaId": "384FD0B4-826D-4A6C-9F78-BC25B9039011",
              "versionEndExcluding": "8.21.0",
              "versionStartIncluding": "7.69.0",
              "vulnerable": true
            }
          ],
          "negate": false,
          "operator": "OR"
        }
      ]
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "When a libcurl-based application performs transfers via `SCP://` or `SFTP://`\nand utilizes the `CURLOPT_SSH_KEYFUNCTION` callback, it may silently accept an\nuntrusted server. This vulnerability occurs when a server presents a host key\ntype that does not match the specific key type already recorded for that host\nin the `known_hosts` file. Instead of rejecting the mismatch, the callback\nmechanism fails to properly enforce the restriction, allowing the connection\nto succeed without warning and risking a potential man-in-the-middle attack."
    }
  ],
  "id": "CVE-2026-9547",
  "lastModified": "2026-09-15T07:16:35.310",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "HIGH",
          "attackVector": "NETWORK",
          "availabilityImpact": "NONE",
          "baseScore": 7.4,
          "baseSeverity": "HIGH",
          "confidentialityImpact": "HIGH",
          "integrityImpact": "HIGH",
          "privilegesRequired": "NONE",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N",
          "version": "3.1"
        },
        "exploitabilityScore": 2.2,
        "impactScore": 5.2,
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "type": "Secondary"
      }
    ],
    "ssvcV203": [
      {
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
          "id": "CVE-2026-9547",
          "options": [
            {
              "exploitation": "poc"
            },
            {
              "automatable": "no"
            },
            {
              "technicalImpact": "total"
            }
          ],
          "role": "CISA Coordinator",
          "timestamp": "2026-07-06T16:47:32.456534Z",
          "version": "2.0.3"
        }
      }
    ]
  },
  "published": "2026-07-03T07:16:25.990",
  "references": [
    {
      "source": "2499f714-1537-4658-8207-48ae4bb9eae9",
      "tags": [
        "Patch",
        "Vendor Advisory"
      ],
      "url": "https://curl.se/docs/CVE-2026-9547.html"
    },
    {
      "source": "2499f714-1537-4658-8207-48ae4bb9eae9",
      "tags": [
        "Vendor Advisory"
      ],
      "url": "https://curl.se/docs/CVE-2026-9547.json"
    },
    {
      "source": "2499f714-1537-4658-8207-48ae4bb9eae9",
      "tags": [
        "Exploit",
        "Issue Tracking",
        "Third Party Advisory"
      ],
      "url": "https://hackerone.com/reports/3751712"
    },
    {
      "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
      "tags": [
        "Exploit",
        "Issue Tracking",
        "Third Party Advisory"
      ],
      "url": "https://hackerone.com/reports/3751712"
    }
  ],
  "sourceIdentifier": "2499f714-1537-4658-8207-48ae4bb9eae9",
  "vulnStatus": "Modified",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-297"
        }
      ],
      "source": "2499f714-1537-4658-8207-48ae4bb9eae9",
      "type": "Secondary"
    },
    {
      "description": [
        {
          "lang": "en",
          "value": "NVD-CWE-Other"
        }
      ],
      "source": "nvd@nist.gov",
      "type": "Primary"
    }
  ]
}



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