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msgpack5: Truncated map32 headers throw an unexpected error

Type: advisorySources: OSV

### Impact A truncated `map32` header causes an out-of-bounds buffer read and throws `RangeError` instead of `IncompleteBufferError`. Applications that rely on `IncompleteBufferError` to wait for additional bytes may terminate a request, stream, or worker unexpectedly. No adjacent memory is disclosed because the buffer implementation checks bounds. ### Patches The decoder now validates the complete five-byte `map32` header before reading its length and reports truncated input as `IncompleteBufferError`. ### Workarounds Require at least five bytes before decoding a value beginning with `0xdf`, or catch `RangeError` and treat it as incomplete input only for truncated `map32` headers.

Products
msgpack5
Affected versions
Not specified
Fixed versions
6.1.0
CVEs
CVE-2026-107302
Confirmed fixed CVEs
Not specified
Updated in this feed
31 Oct 2026, 08:26 UTC · Revision 1

Source evidence

msgpack5: Truncated map32 headers throw an unexpected error

core-osv · Original source

Published 8 Oct 2026, 17:40 UTC

### Impact A truncated `map32` header causes an out-of-bounds buffer read and throws `RangeError` instead of `IncompleteBufferError`. Applications that rely on `IncompleteBufferError` to wait for additional bytes may terminate a request, stream, or worker unexpectedly. No adjacent memory is disclosed because the buffer implementation checks bounds. ### Patches The decoder now validates the complete five-byte `map32` header before reading its length and reports truncated input as `IncompleteBufferError`. ### Workarounds Require at least five bytes before decoding a value beginning with `0xdf`, or catch `RangeError` and treat it as incomplete input only for truncated `map32` headers.

osv:GHSA-8f34-f56x-9xph

msgpack5

Fixed versions: 6.1.0

Complete source record
{
  "id": "0c6885841a02b5f93eae1010d28e66685c450896cc4b7778d7487944e82c96c6",
  "url": "https://osv.dev/vulnerability/GHSA-8f34-f56x-9xph",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "msgpack5: Truncated map32 headers throw an unexpected error",
    "summary": "### Impact A truncated `map32` header causes an out-of-bounds buffer read and throws `RangeError` instead of `IncompleteBufferError`. Applications that rely on `IncompleteBufferError` to wait for additional bytes may terminate a request, stream, or worker unexpectedly. No adjacent memory is disclosed because the buffer implementation checks bounds. ### Patches The decoder now validates the complete five-byte `map32` header before reading its length and reports truncated input as `IncompleteBufferError`. ### Workarounds Require at least five bytes before decoding a value beginning with `0xdf`, or catch `RangeError` and treat it as incomplete input only for truncated `map32` headers.",
    "evidence": "osv:GHSA-8f34-f56x-9xph",
    "products": [
      {
        "name": {
          "value": "msgpack5",
          "evidence": "/affected/0/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "6.1.0",
            "evidence": "/affected/0/ranges"
          }
        ],
        "affected_versions": []
      }
    ],
    "severity": "high",
    "structured": {
      "id": "GHSA-8f34-f56x-9xph",
      "aliases": [
        "CVE-2026-107302",
        "GHSA-8f34-f56x-9xph"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "type": "SEMVER",
              "events": [
                {
                  "introduced": "4.1.0"
                },
                {
                  "fixed": "6.1.0"
                }
              ]
            }
          ],
          "package": {
            "name": "msgpack5",
            "purl": "pkg:npm/msgpack5",
            "ecosystem": "npm"
          },
          "database_specific": {
            "source": "https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/10/GHSA-8f34-f56x-9xph/GHSA-8f34-f56x-9xph.json"
          }
        }
      ],
      "modified": "2026-10-19T19:45:04.408071513Z",
      "provider": "osv",
      "references": [
        "https://github.com/mcollina/msgpack5/security/advisories/GHSA-8f34-f56x-9xph",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-107302",
        "https://github.com/mcollina/msgpack5/commit/15443a1f2aa682a6aa37f1705ac628de5b866ad1",
        "https://github.com/mcollina/msgpack5",
        "https://github.com/mcollina/msgpack5/releases/tag/v6.1.0"
      ],
      "provider_metadata": {
        "cwe_ids": [
          "CWE-125"
        ],
        "severity": "HIGH",
        "github_reviewed": true,
        "nvd_published_at": "2026-10-08T18:17:19Z",
        "github_reviewed_at": "2026-10-08T17:40:10Z"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-107302",
        "evidence": "/aliases"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/database_specific/severity"
  },
  "source_id": "core-osv",
  "document_id": 375760,
  "published_at": "2026-10-08T17:40:10+00:00"
}