{
  "cveId": "CVE-2021-21401",
  "url": "https://patchblox.com/security/cve/CVE-2021-21401",
  "summary": "CVE-2021-21401 is fixed in nanopb on 1 platform by nanopb 0.4.1-1ubuntu0.1~esm1 (version 0.4.1-1ubuntu0.1~esm1), released March 23, 2021. It is not reported as exploited. Patch Radar priority: Routine.",
  "title": "nanopb: Nanopb is a small code-size Protocol Buffers implementation in ansi C",
  "description": "Nanopb is a small code-size Protocol Buffers implementation in ansi C. In Nanopb before versions 0.3.9.8 and 0.4.5, decoding a specifically formed message can cause invalid \u0060free()\u0060 or \u0060realloc()\u0060 calls if the message type contains an \u0060oneof\u0060 field, and the \u0060oneof\u0060 directly contains both a pointer field and a non-pointer field. If the message data first contains the non-pointer field and then the pointer field, the data of the non-pointer field is incorrectly treated as if it was a pointer value. Such message data rarely occurs in normal messages, but it is a concern when untrusted data is parsed. This has been fixed in versions 0.3.9.8 and 0.4.5. See referenced GitHub Security Advisory for more information including workarounds.",
  "published": "2021-03-23T11:15:00Z",
  "severity": "Medium",
  "epss": 0.01811,
  "epssPercentile": 0.78768,
  "priority": "Routine",
  "priorityTier": 4,
  "exploited": false,
  "vendorExploited": false,
  "disclosed": false,
  "fixes": [
    {
      "platform": "linux",
      "product": "nanopb",
      "release": "Ubuntu 20.04 LTS (focal)",
      "fixedVersion": "0.4.1-1ubuntu0.1~esm1",
      "fix": "nanopb 0.4.1-1ubuntu0.1~esm1",
      "url": "https://patchblox.com/security/fix/linux/ubuntu-focal-nanopb-0.4.1-1ubuntu0.1-esm1",
      "released": "2021-03-23T11:15:00Z"
    }
  ],
  "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"
  }
}