{
  "cveId": "CVE-2026-19773",
  "url": "https://patchblox.com/security/cve/CVE-2026-19773",
  "summary": "CVE-2026-19773 is fixed in 10 products on 1 platform, first by libwebsockets-evlib-ev 4.3.5-3ubuntu1.2\u002Besm1, released September 15, 2026. It is not reported as exploited. Patch Radar priority: Urgent.",
  "title": "libwebsockets: libwebsockets HTTP/2 HPACK Path Header Parsing Out-Of-Bounds Write Remote Code Execution Vulnerability",
  "description": "libwebsockets HTTP/2 HPACK Path Header Parsing Out-Of-Bounds Write Remote Code Execution Vulnerability. This vulnerability allows remote attackers to execute arbitrary code on affected installations of libwebsockets. Authentication is not required to exploit this vulnerability.  The specific flaw exists within the parsing of HTTP/2 HPACK path header. The issue results from the lack of proper validation of user-supplied data, which can result in a write past the end of an allocated buffer. An attacker can leverage this vulnerability to execute code in the context of the current process. Was ZDI-CAN-31036.",
  "published": "2026-09-15T12:17:00Z",
  "severity": "critical",
  "cvss": 9.8,
  "cvssVector": "CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
  "epss": 0.00646,
  "epssPercentile": 0.51246,
  "priority": "Urgent",
  "priorityTier": 2,
  "exploited": false,
  "vendorExploited": false,
  "disclosed": false,
  "fixes": [
    {
      "platform": "linux",
      "product": "libwebsockets",
      "release": "Debian 13.5 (trixie)",
      "fixedVersion": "4.3.5-1\u002Bdeb13u3",
      "fix": "DEBIAN-CVE-2026-19773",
      "url": "https://patchblox.com/security/fix/linux/debian-cve-2026-19773",
      "released": "2026-09-30T20:39:22Z"
    },
    {
      "platform": "linux",
      "product": "libwebsockets",
      "release": "Debian 14",
      "fixedVersion": "4.3.5-7",
      "fix": "DEBIAN-CVE-2026-19773",
      "url": "https://patchblox.com/security/fix/linux/debian-cve-2026-19773",
      "released": "2026-09-30T20:39:22Z"
    },
    {
      "platform": "linux",
      "product": "libwebsockets-evlib-ev",
      "release": "Ubuntu 24.04.5 LTS (noble)",
      "fixedVersion": "4.3.3-1.1ubuntu0.1~esm3",
      "fix": "libwebsockets-evlib-ev 4.3.3-1.1ubuntu0.1~esm3",
      "url": "https://patchblox.com/security/fix/linux/ubuntu-noble-libwebsockets-evlib-ev-4.3.3-1.1ubuntu0.1-esm3",
      "released": "2026-10-08T22:21:53Z"
    },
    {
      "platform": "linux",
      "product": "libwebsockets-evlib-ev",
      "release": "Ubuntu 26.04.1 LTS (resolute)",
      "fixedVersion": "4.3.5-3ubuntu1.2\u002Besm1",
      "fix": "libwebsockets-evlib-ev 4.3.5-3ubuntu1.2\u002Besm1",
      "url": "https://patchblox.com/security/fix/linux/ubuntu-resolute-libwebsockets-evlib-ev-4.3.5-3ubuntu1.2-esm1",
      "released": "2026-09-15T12:17:00Z"
    },
    {
      "platform": "linux",
      "product": "libwebsockets-evlib-glib",
      "release": "Ubuntu 24.04.5 LTS (noble)",
      "fixedVersion": "4.3.3-1.1ubuntu0.1~esm3",
      "fix": "libwebsockets-evlib-glib 4.3.3-1.1ubuntu0.1~esm3",
      "url": "https://patchblox.com/security/fix/linux/ubuntu-noble-libwebsockets-evlib-glib-4.3.3-1.1ubuntu0.1-esm3",
      "released": "2026-10-08T22:21:53Z"
    },
    {
      "platform": "linux",
      "product": "libwebsockets-evlib-glib",
      "release": "Ubuntu 26.04.1 LTS (resolute)",
      "fixedVersion": "4.3.5-3ubuntu1.2\u002Besm1",
      "fix": "libwebsockets-evlib-glib 4.3.5-3ubuntu1.2\u002Besm1",
      "url": "https://patchblox.com/security/fix/linux/ubuntu-resolute-libwebsockets-evlib-glib-4.3.5-3ubuntu1.2-esm1",
      "released": "2026-09-15T12:17:00Z"
    },
    {
      "platform": "linux",
      "product": "libwebsockets-evlib-uv",
      "release": "Ubuntu 24.04.5 LTS (noble)",
      "fixedVersion": "4.3.3-1.1ubuntu0.1~esm3",
      "fix": "libwebsockets-evlib-uv 4.3.3-1.1ubuntu0.1~esm3",
      "url": "https://patchblox.com/security/fix/linux/ubuntu-noble-libwebsockets-evlib-uv-4.3.3-1.1ubuntu0.1-esm3",
      "released": "2026-10-08T22:21:53Z"
    },
    {
      "platform": "linux",
      "product": "libwebsockets-evlib-uv",
      "release": "Ubuntu 26.04.1 LTS (resolute)",
      "fixedVersion": "4.3.5-3ubuntu1.2\u002Besm1",
      "fix": "libwebsockets-evlib-uv 4.3.5-3ubuntu1.2\u002Besm1",
      "url": "https://patchblox.com/security/fix/linux/ubuntu-resolute-libwebsockets-evlib-uv-4.3.5-3ubuntu1.2-esm1",
      "released": "2026-09-15T12:17:00Z"
    },
    {
      "platform": "linux",
      "product": "libwebsockets-test-server",
      "release": "Ubuntu 18.04.6 LTS (bionic)",
      "fixedVersion": "2.0.3-3ubuntu0.1~esm1",
      "fix": "libwebsockets-test-server 2.0.3-3ubuntu0.1~esm1",
      "url": "https://patchblox.com/security/fix/linux/ubuntu-bionic-libwebsockets-test-server-2.0.3-3ubuntu0.1-esm1",
      "released": "2026-10-08T22:21:45Z"
    },
    {
      "platform": "linux",
      "product": "libwebsockets-test-server",
      "release": "Ubuntu 20.04 LTS (focal)",
      "fixedVersion": "3.2.1-3ubuntu0.1~esm3",
      "fix": "libwebsockets-test-server 3.2.1-3ubuntu0.1~esm3",
      "url": "https://patchblox.com/security/fix/linux/ubuntu-focal-libwebsockets-test-server-3.2.1-3ubuntu0.1-esm3",
      "released": "2026-10-08T22:21:48Z"
    },
    {
      "platform": "linux",
      "product": "libwebsockets-test-server",
      "release": "Ubuntu 22.04.1 LTS (jammy)",
      "fixedVersion": "4.0.20-2ubuntu1.1\u002Besm2",
      "fix": "libwebsockets-test-server 4.0.20-2ubuntu1.1\u002Besm2",
      "url": "https://patchblox.com/security/fix/linux/ubuntu-jammy-libwebsockets-test-server-4.0.20-2ubuntu1.1-esm2",
      "released": "2026-10-08T22:21:53Z"
    },
    {
      "platform": "linux",
      "product": "libwebsockets-test-server",
      "release": "Ubuntu 24.04.5 LTS (noble)",
      "fixedVersion": "4.3.3-1.1ubuntu0.1~esm3",
      "fix": "libwebsockets-test-server 4.3.3-1.1ubuntu0.1~esm3",
      "url": "https://patchblox.com/security/fix/linux/ubuntu-noble-libwebsockets-test-server-4.3.3-1.1ubuntu0.1-esm3",
      "released": "2026-10-08T22:21:53Z"
    },
    {
      "platform": "linux",
      "product": "libwebsockets-test-server",
      "release": "Ubuntu 26.04.1 LTS (resolute)",
      "fixedVersion": "4.3.5-3ubuntu1.2\u002Besm1",
      "fix": "libwebsockets-test-server 4.3.5-3ubuntu1.2\u002Besm1",
      "url": "https://patchblox.com/security/fix/linux/ubuntu-resolute-libwebsockets-test-server-4.3.5-3ubuntu1.2-esm1",
      "released": "2026-09-15T12:17:00Z"
    },
    {
      "platform": "linux",
      "product": "libwebsockets-test-server-common",
      "release": "Ubuntu 18.04.6 LTS (bionic)",
      "fixedVersion": "2.0.3-3ubuntu0.1~esm1",
      "fix": "libwebsockets-test-server-common 2.0.3-3ubuntu0.1~esm1",
      "url": "https://patchblox.com/security/fix/linux/ubuntu-bionic-libwebsockets-test-server-common-2.0.3-3ubuntu0.1-esm1",
      "released": "2026-10-08T22:21:45Z"
    },
    {
      "platform": "linux",
      "product": "libwebsockets-test-server-common",
      "release": "Ubuntu 20.04 LTS (focal)",
      "fixedVersion": "3.2.1-3ubuntu0.1~esm3",
      "fix": "libwebsockets-test-server-common 3.2.1-3ubuntu0.1~esm3",
      "url": "https://patchblox.com/security/fix/linux/ubuntu-focal-libwebsockets-test-server-common-3.2.1-3ubuntu0.1-esm3",
      "released": "2026-10-08T22:21:48Z"
    },
    {
      "platform": "linux",
      "product": "libwebsockets-test-server-common",
      "release": "Ubuntu 22.04.1 LTS (jammy)",
      "fixedVersion": "4.0.20-2ubuntu1.1\u002Besm2",
      "fix": "libwebsockets-test-server-common 4.0.20-2ubuntu1.1\u002Besm2",
      "url": "https://patchblox.com/security/fix/linux/ubuntu-jammy-libwebsockets-test-server-common-4.0.20-2ubuntu1.1-esm2",
      "released": "2026-10-08T22:21:53Z"
    },
    {
      "platform": "linux",
      "product": "libwebsockets-test-server-common",
      "release": "Ubuntu 24.04.5 LTS (noble)",
      "fixedVersion": "4.3.3-1.1ubuntu0.1~esm3",
      "fix": "libwebsockets-test-server-common 4.3.3-1.1ubuntu0.1~esm3",
      "url": "https://patchblox.com/security/fix/linux/ubuntu-noble-libwebsockets-test-server-common-4.3.3-1.1ubuntu0.1-esm3",
      "released": "2026-10-08T22:21:53Z"
    },
    {
      "platform": "linux",
      "product": "libwebsockets-test-server-common",
      "release": "Ubuntu 26.04.1 LTS (resolute)",
      "fixedVersion": "4.3.5-3ubuntu1.2\u002Besm1",
      "fix": "libwebsockets-test-server-common 4.3.5-3ubuntu1.2\u002Besm1",
      "url": "https://patchblox.com/security/fix/linux/ubuntu-resolute-libwebsockets-test-server-common-4.3.5-3ubuntu1.2-esm1",
      "released": "2026-09-15T12:17:00Z"
    },
    {
      "platform": "linux",
      "product": "libwebsockets15",
      "release": "Ubuntu 20.04 LTS (focal)",
      "fixedVersion": "3.2.1-3ubuntu0.1~esm3",
      "fix": "libwebsockets15 3.2.1-3ubuntu0.1~esm3",
      "url": "https://patchblox.com/security/fix/linux/ubuntu-focal-libwebsockets15-3.2.1-3ubuntu0.1-esm3",
      "released": "2026-10-08T22:21:48Z"
    },
    {
      "platform": "linux",
      "product": "libwebsockets16",
      "release": "Ubuntu 22.04.1 LTS (jammy)",
      "fixedVersion": "4.0.20-2ubuntu1.1\u002Besm2",
      "fix": "libwebsockets16 4.0.20-2ubuntu1.1\u002Besm2",
      "url": "https://patchblox.com/security/fix/linux/ubuntu-jammy-libwebsockets16-4.0.20-2ubuntu1.1-esm2",
      "released": "2026-10-08T22:21:53Z"
    },
    {
      "platform": "linux",
      "product": "libwebsockets19t64",
      "release": "Ubuntu 24.04.5 LTS (noble)",
      "fixedVersion": "4.3.3-1.1ubuntu0.1~esm3",
      "fix": "libwebsockets19t64 4.3.3-1.1ubuntu0.1~esm3",
      "url": "https://patchblox.com/security/fix/linux/ubuntu-noble-libwebsockets19t64-4.3.3-1.1ubuntu0.1-esm3",
      "released": "2026-10-08T22:21:53Z"
    },
    {
      "platform": "linux",
      "product": "libwebsockets19t64",
      "release": "Ubuntu 26.04.1 LTS (resolute)",
      "fixedVersion": "4.3.5-3ubuntu1.2\u002Besm1",
      "fix": "libwebsockets19t64 4.3.5-3ubuntu1.2\u002Besm1",
      "url": "https://patchblox.com/security/fix/linux/ubuntu-resolute-libwebsockets19t64-4.3.5-3ubuntu1.2-esm1",
      "released": "2026-09-15T12:17:00Z"
    },
    {
      "platform": "linux",
      "product": "libwebsockets8",
      "release": "Ubuntu 18.04.6 LTS (bionic)",
      "fixedVersion": "2.0.3-3ubuntu0.1~esm1",
      "fix": "libwebsockets8 2.0.3-3ubuntu0.1~esm1",
      "url": "https://patchblox.com/security/fix/linux/ubuntu-bionic-libwebsockets8-2.0.3-3ubuntu0.1-esm1",
      "released": "2026-10-08T22:21:45Z"
    }
  ],
  "noFixYet": [],
  "dataAsOf": "2026-11-09T01:18:40Z",
  "attribution": {
    "text": "Data: Patchblox Patch Radar",
    "url": "https://patchblox.com/security/patch-radar",
    "terms": "https://patchblox.com/security/patch-radar/use-the-data"
  }
}