UBUNTU-CVE-2026-12064 (CVE-2026-12064)

Vulnerability from osv_ubuntu – Published: 2026-06-24 14:00 – Updated: 2026-07-10 22:21 – Source website
VLAI
Details

When a user invokes curl using a schemeless URL combined with --proto-default sftp (or scp), a disconnect occurs between the tool layer and libcurl. The tool layer incorrectly infers the URL scheme, which erroneously bypasses the initialization of critical SSH security options like CURLOPT_SSH_HOST_PUBLIC_KEY_SHA256 and CURLOPT_SSH_KNOWNHOSTS. Conversely, the libcurl runtime successfully honors CURLOPT_DEFAULT_PROTOCOL and establishes the connection via SFTP/SCP as specified. Because the tool layer skipped the security configuration, these SSH host verification options are silently omitted, causing curl to connect to an unverified SSH remote host without throwing an error.

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

{
  "affected": [
    {
      "ecosystem_specific": {
        "availability": "No subscription required",
        "binaries": [
          {
            "binary_name": "curl",
            "binary_version": "8.14.1-2ubuntu1.5"
          },
          {
            "binary_name": "libcurl3t64-gnutls",
            "binary_version": "8.14.1-2ubuntu1.5"
          },
          {
            "binary_name": "libcurl4t64",
            "binary_version": "8.14.1-2ubuntu1.5"
          }
        ],
        "priority_reason": "Upstream defined this as low severity"
      },
      "package": {
        "ecosystem": "Ubuntu:25.10",
        "name": "curl",
        "purl": "pkg:deb/ubuntu/curl@8.14.1-2ubuntu1.5?arch=source\u0026distro=questing"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "8.14.1-2ubuntu1.5"
            }
          ],
          "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",
        "8.14.1-2ubuntu1.4"
      ]
    },
    {
      "ecosystem_specific": {
        "availability": "No subscription required",
        "binaries": [
          {
            "binary_name": "curl",
            "binary_version": "8.18.0-1ubuntu2.3"
          },
          {
            "binary_name": "libcurl3t64-gnutls",
            "binary_version": "8.18.0-1ubuntu2.3"
          },
          {
            "binary_name": "libcurl4t64",
            "binary_version": "8.18.0-1ubuntu2.3"
          }
        ],
        "priority_reason": "Upstream defined this as low severity"
      },
      "package": {
        "ecosystem": "Ubuntu:26.04:LTS",
        "name": "curl",
        "purl": "pkg:deb/ubuntu/curl@8.18.0-1ubuntu2.3?arch=source\u0026distro=resolute"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "8.18.0-1ubuntu2.3"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "8.14.1-2ubuntu1",
        "8.17.0-1ubuntu1",
        "8.18.0-1ubuntu1",
        "8.18.0-1ubuntu2",
        "8.18.0-1ubuntu2.1",
        "8.18.0-1ubuntu2.2"
      ]
    }
  ],
  "aliases": [],
  "details": "When a user invokes curl using a schemeless URL combined with `--proto-default` sftp (or scp), a disconnect occurs between the tool layer and libcurl. The tool layer incorrectly infers the URL scheme, which erroneously bypasses the initialization of critical SSH security options like CURLOPT_SSH_HOST_PUBLIC_KEY_SHA256 and CURLOPT_SSH_KNOWNHOSTS. Conversely, the libcurl runtime successfully honors CURLOPT_DEFAULT_PROTOCOL and establishes the connection via SFTP/SCP as specified. Because the tool layer skipped the security configuration, these SSH host verification options are silently omitted, causing curl to connect to an unverified SSH remote host without throwing an error.",
  "id": "UBUNTU-CVE-2026-12064",
  "modified": "2026-07-10T22:21:40Z",
  "published": "2026-06-24T14:00:00Z",
  "references": [
    {
      "type": "REPORT",
      "url": "https://ubuntu.com/security/CVE-2026-12064"
    },
    {
      "type": "REPORT",
      "url": "https://www.cve.org/CVERecord?id=CVE-2026-12064"
    },
    {
      "type": "REPORT",
      "url": "https://curl.se/L7HzKXisfJ/CVE-2026-12064.md"
    },
    {
      "type": "ADVISORY",
      "url": "https://ubuntu.com/security/notices/USN-8525-1"
    }
  ],
  "related": [
    "USN-8525-1"
  ],
  "schema_version": "1.7.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N",
      "type": "CVSS_V3"
    },
    {
      "score": "low",
      "type": "Ubuntu"
    }
  ],
  "upstream": [
    "CVE-2026-12064"
  ]
}



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