{
  "cveId": "CVE-2021-20235",
  "url": "https://patchblox.com/security/cve/CVE-2021-20235",
  "summary": "CVE-2021-20235 is fixed in libzmq5 on 1 platform, first by libzmq5 4.2.5-1ubuntu0.2\u002Besm2, released May 28, 2021. It is not reported as exploited. Patch Radar priority: Routine.",
  "title": "libzmq5: There\u0027s a flaw in the zeromq server in versions before 4.3.3 in src/decoder_allocators.hpp",
  "description": "There\u0027s a flaw in the zeromq server in versions before 4.3.3 in src/decoder_allocators.hpp. The decoder static allocator could have its sized changed, but the buffer would remain the same as it is a static buffer. A remote, unauthenticated attacker who sends a crafted request to the zeromq server could trigger a buffer overflow WRITE of arbitrary data if CURVE/ZAP authentication is not enabled. The greatest impact of this flaw is to application availability, data integrity, and confidentiality.",
  "published": "2021-04-01T07:15:00Z",
  "severity": "Medium",
  "epss": 0.43862,
  "epssPercentile": 0.98756,
  "priority": "Routine",
  "priorityTier": 4,
  "exploited": false,
  "vendorExploited": false,
  "disclosed": false,
  "fixes": [
    {
      "platform": "linux",
      "product": "libzmq5",
      "release": "Ubuntu 18.04.6 LTS (bionic)",
      "fixedVersion": "4.2.5-1ubuntu0.2\u002Besm2",
      "fix": "libzmq5 4.2.5-1ubuntu0.2\u002Besm2",
      "url": "https://patchblox.com/security/fix/linux/ubuntu-bionic-libzmq5-4.2.5-1ubuntu0.2-esm2",
      "released": "2021-05-28T04:15:00Z"
    },
    {
      "platform": "linux",
      "product": "libzmq5",
      "release": "Ubuntu 20.04 LTS (focal)",
      "fixedVersion": "4.3.2-2ubuntu1.20.04.1~esm2",
      "fix": "libzmq5 4.3.2-2ubuntu1.20.04.1~esm2",
      "url": "https://patchblox.com/security/fix/linux/ubuntu-focal-libzmq5-4.3.2-2ubuntu1.20.04.1-esm2",
      "released": "2021-05-28T04:15:00Z"
    }
  ],
  "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"
  }
}