{
  "cveId": "CVE-2026-55199",
  "url": "https://patchblox.com/security/cve/CVE-2026-55199",
  "summary": "CVE-2026-55199 is fixed in 7 products on 1 platform, first by libssh2-1t64 1.11.1-1ubuntu0.26.04.2, released June 18, 2026. It is not reported as exploited. Patch Radar priority: High.",
  "title": "libssh2 - Pre-Authentication DoS via SSH_MSG_EXT_INFO Handler",
  "description": "libssh2 through 1.11.1, fixed in commit 1762685, contains a pre-authentication denial of service vulnerability in the SSH_MSG_EXT_INFO handler in src/packet.c that allows a malicious SSH server to cause a client CPU exhaustion loop by sending a crafted extension count value. A malicious server can set nr_extensions to 0xFFFFFFFF during key exchange, causing the client to spin in a tight CPU loop for over 60 seconds because return values from _libssh2_get_string() are unchecked and the session timeout does not apply to CPU-bound loops.",
  "published": "2026-06-17T13:17:00Z",
  "severity": "Important",
  "cvss": 7.5,
  "cvssVector": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
  "cwe": "Loop with Unreachable Exit Condition (\u0027Infinite Loop\u0027)",
  "epss": 0.00918,
  "epssPercentile": 0.60466,
  "priority": "High",
  "priorityTier": 3,
  "exploited": false,
  "vendorExploited": false,
  "disclosed": false,
  "vendorAdvisory": "https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-55199",
  "fixes": [
    {
      "platform": "linux",
      "product": "libssh2",
      "release": "Debian 13.5 (trixie)",
      "fixedVersion": "1.11.1-1\u002Bdeb13u1",
      "fix": "DEBIAN-CVE-2026-55199",
      "url": "https://patchblox.com/security/fix/linux/debian-cve-2026-55199",
      "released": "2026-06-26T17:32:29Z"
    },
    {
      "platform": "linux",
      "product": "libssh2",
      "release": "Debian 14",
      "fixedVersion": "1.11.1-4",
      "fix": "DEBIAN-CVE-2026-55199",
      "url": "https://patchblox.com/security/fix/linux/debian-cve-2026-55199",
      "released": "2026-06-26T17:32:29Z"
    },
    {
      "platform": "linux",
      "product": "libssh2",
      "release": "Fedora 43",
      "fixedVersion": "1.11.1-9.fc43",
      "fix": "FEDORA-2026-EED9E67393",
      "url": "https://patchblox.com/security/fix/linux/fedora-2026-eed9e67393",
      "released": "2026-06-24T17:21:03Z"
    },
    {
      "platform": "linux",
      "product": "libssh2-1t64",
      "release": "Ubuntu 24.04.5 LTS (noble)",
      "fixedVersion": "1.11.0-4.1ubuntu0.24.04.2",
      "fix": "libssh2-1t64 1.11.0-4.1ubuntu0.24.04.2",
      "url": "https://patchblox.com/security/fix/linux/ubuntu-noble-libssh2-1t64-1.11.0-4.1ubuntu0.24.04.2",
      "released": "2026-07-03T14:54:52Z"
    },
    {
      "platform": "linux",
      "product": "libssh2-1t64",
      "release": "Ubuntu 25.10 (questing)",
      "fixedVersion": "1.11.1-1ubuntu0.25.10.2",
      "fix": "libssh2-1t64 1.11.1-1ubuntu0.25.10.2",
      "url": "https://patchblox.com/security/fix/linux/ubuntu-questing-libssh2-1t64-1.11.1-1ubuntu0.25.10.2",
      "released": "2026-07-03T14:54:55Z"
    },
    {
      "platform": "linux",
      "product": "libssh2-1t64",
      "release": "Ubuntu 26.04.1 LTS (resolute)",
      "fixedVersion": "1.11.1-1ubuntu0.26.04.2",
      "fix": "libssh2-1t64 1.11.1-1ubuntu0.26.04.2",
      "url": "https://patchblox.com/security/fix/linux/ubuntu-resolute-libssh2-1t64-1.11.1-1ubuntu0.26.04.2",
      "released": "2026-06-18T14:16:00Z"
    },
    {
      "platform": "linux",
      "product": "libssh2-debuginfo",
      "release": "Fedora 43",
      "fixedVersion": "1.11.1-9.fc43",
      "fix": "FEDORA-2026-EED9E67393",
      "url": "https://patchblox.com/security/fix/linux/fedora-2026-eed9e67393",
      "released": "2026-06-24T17:21:03Z"
    },
    {
      "platform": "linux",
      "product": "libssh2-debugsource",
      "release": "Fedora 43",
      "fixedVersion": "1.11.1-9.fc43",
      "fix": "FEDORA-2026-EED9E67393",
      "url": "https://patchblox.com/security/fix/linux/fedora-2026-eed9e67393",
      "released": "2026-06-24T17:21:03Z"
    },
    {
      "platform": "linux",
      "product": "libssh2-devel",
      "release": "Fedora 43",
      "fixedVersion": "1.11.1-9.fc43",
      "fix": "FEDORA-2026-EED9E67393",
      "url": "https://patchblox.com/security/fix/linux/fedora-2026-eed9e67393",
      "released": "2026-06-24T17:21:03Z"
    },
    {
      "platform": "linux",
      "product": "libssh2-docs",
      "release": "Fedora 43",
      "fixedVersion": "1.11.1-9.fc43",
      "fix": "FEDORA-2026-EED9E67393",
      "url": "https://patchblox.com/security/fix/linux/fedora-2026-eed9e67393",
      "released": "2026-06-24T17:21:03Z"
    },
    {
      "platform": "linux",
      "product": "libssh2_org",
      "release": "opensuse-leap 16.0",
      "fixedVersion": "1.11.1-160000.4.1",
      "fix": "OPENSUSE-SU-2026:21057-1",
      "url": "https://patchblox.com/security/fix/linux/opensuse-su-2026-21057-1",
      "released": "2026-06-25T11:51:43Z"
    },
    {
      "platform": "linux",
      "product": "libssh2_org",
      "release": "sles 15.6",
      "fixedVersion": "1.11.0-150600.20.3.1",
      "fix": "SUSE-SU-2026:3076-1",
      "url": "https://patchblox.com/security/fix/linux/suse-su-2026-3076-1",
      "released": "2026-07-16T13:04:25Z"
    },
    {
      "platform": "linux",
      "product": "libssh2_org",
      "release": "sles 15.7",
      "fixedVersion": "1.11.0-150600.20.3.1",
      "fix": "SUSE-SU-2026:3076-1",
      "url": "https://patchblox.com/security/fix/linux/suse-su-2026-3076-1",
      "released": "2026-07-16T13:04:25Z"
    },
    {
      "platform": "linux",
      "product": "libssh2_org",
      "release": "sles 16.0",
      "fixedVersion": "1.11.1-160000.4.1",
      "fix": "SUSE-SU-2026:22364-1",
      "url": "https://patchblox.com/security/fix/linux/suse-su-2026-22364-1",
      "released": "2026-06-25T11:50:54Z"
    }
  ],
  "noFixYet": [],
  "dataAsOf": "2026-11-08T06:59:42Z",
  "attribution": {
    "text": "Data: Patchblox Patch Radar",
    "url": "https://patchblox.com/security/patch-radar",
    "terms": "https://patchblox.com/security/patch-radar/use-the-data"
  }
}