UBUNTU-CVE-2026-9547 (CVE-2026-9547)

Vulnerability from osv_ubuntu – Published: 2026-06-24 14:00 – Updated: 2026-07-08 07:51 – Source website
VLAI
Details

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.

Severity
7.4 (High)
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N
N/A (UNKNOWN)
low
References
To clipboard 

{
  "affected": [
    {
      "ecosystem_specific": {
        "availability": "No subscription required",
        "binaries": [
          {
            "binary_name": "curl",
            "binary_version": "7.81.0-1ubuntu1.25"
          },
          {
            "binary_name": "libcurl3-gnutls",
            "binary_version": "7.81.0-1ubuntu1.25"
          },
          {
            "binary_name": "libcurl3-nss",
            "binary_version": "7.81.0-1ubuntu1.25"
          },
          {
            "binary_name": "libcurl4",
            "binary_version": "7.81.0-1ubuntu1.25"
          }
        ],
        "priority_reason": "Upstream defined this as low severity"
      },
      "package": {
        "ecosystem": "Ubuntu:22.04:LTS",
        "name": "curl",
        "purl": "pkg:deb/ubuntu/curl@7.81.0-1ubuntu1.25?arch=source\u0026distro=jammy"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "7.81.0-1ubuntu1.25"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "7.74.0-1.3ubuntu2",
        "7.74.0-1.3ubuntu3",
        "7.80.0-3",
        "7.81.0-1",
        "7.81.0-1ubuntu1.1",
        "7.81.0-1ubuntu1.2",
        "7.81.0-1ubuntu1.3",
        "7.81.0-1ubuntu1.4",
        "7.81.0-1ubuntu1.6",
        "7.81.0-1ubuntu1.7",
        "7.81.0-1ubuntu1.8",
        "7.81.0-1ubuntu1.10",
        "7.81.0-1ubuntu1.11",
        "7.81.0-1ubuntu1.13",
        "7.81.0-1ubuntu1.14",
        "7.81.0-1ubuntu1.15",
        "7.81.0-1ubuntu1.16",
        "7.81.0-1ubuntu1.17",
        "7.81.0-1ubuntu1.18",
        "7.81.0-1ubuntu1.19",
        "7.81.0-1ubuntu1.20",
        "7.81.0-1ubuntu1.21",
        "7.81.0-1ubuntu1.22",
        "7.81.0-1ubuntu1.23",
        "7.81.0-1ubuntu1.24"
      ]
    },
    {
      "ecosystem_specific": {
        "availability": "No subscription required",
        "binaries": [
          {
            "binary_name": "curl",
            "binary_version": "8.5.0-2ubuntu10.10"
          },
          {
            "binary_name": "libcurl3t64-gnutls",
            "binary_version": "8.5.0-2ubuntu10.10"
          },
          {
            "binary_name": "libcurl4t64",
            "binary_version": "8.5.0-2ubuntu10.10"
          }
        ],
        "priority_reason": "Upstream defined this as low severity"
      },
      "package": {
        "ecosystem": "Ubuntu:24.04:LTS",
        "name": "curl",
        "purl": "pkg:deb/ubuntu/curl@8.5.0-2ubuntu10.10?arch=source\u0026distro=noble"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "8.5.0-2ubuntu10.10"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "8.2.1-1ubuntu3",
        "8.2.1-1ubuntu3.1",
        "8.4.0-2ubuntu1",
        "8.5.0-2ubuntu1",
        "8.5.0-2ubuntu2",
        "8.5.0-2ubuntu8",
        "8.5.0-2ubuntu9",
        "8.5.0-2ubuntu10",
        "8.5.0-2ubuntu10.1",
        "8.5.0-2ubuntu10.2",
        "8.5.0-2ubuntu10.3",
        "8.5.0-2ubuntu10.4",
        "8.5.0-2ubuntu10.5",
        "8.5.0-2ubuntu10.6",
        "8.5.0-2ubuntu10.7",
        "8.5.0-2ubuntu10.8",
        "8.5.0-2ubuntu10.9"
      ]
    },
    {
      "ecosystem_specific": {
        "availability": "No subscription required",
        "binaries": [
          {
            "binary_name": "curl",
            "binary_version": "8.14.1-2ubuntu1.4"
          },
          {
            "binary_name": "libcurl3t64-gnutls",
            "binary_version": "8.14.1-2ubuntu1.4"
          },
          {
            "binary_name": "libcurl4t64",
            "binary_version": "8.14.1-2ubuntu1.4"
          }
        ],
        "priority_reason": "Upstream defined this as low severity"
      },
      "package": {
        "ecosystem": "Ubuntu:25.10",
        "name": "curl",
        "purl": "pkg:deb/ubuntu/curl@8.14.1-2ubuntu1.4?arch=source\u0026distro=questing"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "8.14.1-2ubuntu1.4"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "8.12.1-3ubuntu1",
        "8.13.0-5ubuntu1",
        "8.14.1-1ubuntu2",
        "8.14.1-1ubuntu3",
        "8.14.1-2ubuntu1",
        "8.14.1-2ubuntu1.1",
        "8.14.1-2ubuntu1.2",
        "8.14.1-2ubuntu1.3"
      ]
    },
    {
      "ecosystem_specific": {
        "availability": "No subscription required",
        "binaries": [
          {
            "binary_name": "curl",
            "binary_version": "8.18.0-1ubuntu2.2"
          },
          {
            "binary_name": "libcurl3t64-gnutls",
            "binary_version": "8.18.0-1ubuntu2.2"
          },
          {
            "binary_name": "libcurl4t64",
            "binary_version": "8.18.0-1ubuntu2.2"
          }
        ],
        "priority_reason": "Upstream defined this as low severity"
      },
      "package": {
        "ecosystem": "Ubuntu:26.04:LTS",
        "name": "curl",
        "purl": "pkg:deb/ubuntu/curl@8.18.0-1ubuntu2.2?arch=source\u0026distro=resolute"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "8.18.0-1ubuntu2.2"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "8.14.1-2ubuntu1",
        "8.17.0-1ubuntu1",
        "8.18.0-1ubuntu1",
        "8.18.0-1ubuntu2",
        "8.18.0-1ubuntu2.1"
      ]
    }
  ],
  "aliases": [],
  "details": "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.",
  "id": "UBUNTU-CVE-2026-9547",
  "modified": "2026-07-08T07:51:40Z",
  "published": "2026-06-24T14:00:00Z",
  "references": [
    {
      "type": "REPORT",
      "url": "https://ubuntu.com/security/CVE-2026-9547"
    },
    {
      "type": "REPORT",
      "url": "https://www.cve.org/CVERecord?id=CVE-2026-9547"
    },
    {
      "type": "REPORT",
      "url": "https://curl.se/L7HzKXisfJ/CVE-2026-9547.md"
    },
    {
      "type": "ADVISORY",
      "url": "https://ubuntu.com/security/notices/USN-8487-1"
    }
  ],
  "related": [
    "USN-8487-1"
  ],
  "schema_version": "1.7.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N",
      "type": "CVSS_V3"
    },
    {
      "score": "low",
      "type": "Ubuntu"
    }
  ],
  "upstream": [
    "CVE-2026-9547"
  ]
}



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