{
  "cveId": "CVE-2026-72854",
  "url": "https://patchblox.com/security/cve/CVE-2026-72854",
  "summary": "CVE-2026-72854 is fixed in msgpack-c on 1 platform, first by DEBIAN-CVE-2026-72854, released August 20, 2026. It is not reported as exploited. Patch Radar priority: Routine.",
  "title": "msgpack-c Integer Overflow in msgpack_unpacker_expand_buffer Causes a False-Success Undersized Reservation",
  "description": "msgpack_unpacker_expand_buffer in src/unpack.c, reached through the public msgpack_unpacker_reserve_buffer API, computes its new buffer size using an unchecked size_t addition of the requested size and the amount already used. The doubling loop guards its own multiplication against overflow, but the addition in the loop condition is unguarded, so a request near SIZE_MAX wraps: the loop condition is already satisfied, the allocation is performed at the small pre-wrap size, and the function returns true. The caller is told the requested capacity was reserved when it was not, so a subsequent write of the requested length overflows the heap buffer. The library\u0027s own example/lib_buffer_unpack.c demonstrates the reserve-then-write pattern, and its defensive assert comparing capacity against the request is compiled out under NDEBUG. msgpack-c\u0027s own decode entry points do not derive the reservation size from untrusted input, so reaching this requires an integration that passes an attacker-influenced length to the reservation API, such as a length-prefixed streaming transport.",
  "published": "2026-08-20T19:17:01Z",
  "severity": "Moderate",
  "cvss": 5.3,
  "cvssVector": "CVSS:3.1/AV:L/AC:H/PR:N/UI:R/S:U/C:N/I:H/A:L",
  "cwe": "Integer Overflow or Wraparound",
  "epss": 0.00157,
  "epssPercentile": 0.04837,
  "priority": "Routine",
  "priorityTier": 4,
  "exploited": false,
  "vendorExploited": false,
  "disclosed": false,
  "vendorAdvisory": "https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-72854",
  "fixes": [
    {
      "platform": "linux",
      "product": "msgpack-c",
      "release": "Debian 14",
      "fixedVersion": "7.0.2-1",
      "fix": "DEBIAN-CVE-2026-72854",
      "url": "https://patchblox.com/security/fix/linux/debian-cve-2026-72854",
      "released": "2026-08-20T19:17:01Z"
    },
    {
      "platform": "linux",
      "product": "msgpack-c",
      "release": "opensuse-leap 16.0",
      "fixedVersion": "7.0.2-160000.1.1",
      "fix": "OPENSUSE-SU-2026:21768-1",
      "url": "https://patchblox.com/security/fix/linux/opensuse-su-2026-21768-1",
      "released": "2026-09-06T16:46:14Z"
    },
    {
      "platform": "linux",
      "product": "msgpack-c",
      "release": "sles 16.0",
      "fixedVersion": "7.0.2-160000.1.1",
      "fix": "SUSE-SU-2026:23630-1",
      "url": "https://patchblox.com/security/fix/linux/suse-su-2026-23630-1",
      "released": "2026-09-06T16:45:50Z"
    }
  ],
  "noFixYet": [],
  "dataAsOf": "2026-11-10T01:44:33Z",
  "attribution": {
    "text": "Data: Patchblox Patch Radar",
    "url": "https://patchblox.com/security/patch-radar",
    "terms": "https://patchblox.com/security/patch-radar/use-the-data"
  }
}