{
  "affected": [
    {
      "ranges": [
        {
          "database_specific": {
            "extracted_events": [
              {
                "introduced": "0"
              },
              {
                "fixed": "16.0.0"
              }
            ],
            "source": [
              "AFFECTED_FIELD",
              "REFERENCES"
            ]
          },
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "773dd80ded24dbd6b19e675c89fd2f3b45f2d899"
            },
            {
              "fixed": "08eb47154168f894a0b4847dcf4f42ff52e8420e"
            }
          ],
          "repo": "https://github.com/libp2p/js-libp2p",
          "type": "GIT"
        }
      ]
    }
  ],
  "aliases": [
    "GHSA-cwc9-cp4j-mcvv"
  ],
  "database_specific": {
    "cna_assigner": "GitHub_M",
    "cwe_ids": [
      "CWE-770"
    ],
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/49xxx/CVE-2026-49866.json"
  },
  "details": "libp2p is a JavaScript Implementation of libp2p networking stack. Prior to 16.0.0, @libp2p/gossipsub defaultDecodeRpcLimits set maxIhaveMessageIDs and maxIwantMessageIDs to Infinity, allowing oversized IHAVE and IWANT control message arrays in message/decodeRpc.ts and gossipsub.ts to synchronously iterate roughly 180,000 message IDs per 4 MB frame and block the Node.js event loop. This issue is fixed in version 16.0.0.",
  "id": "CVE-2026-49866",
  "modified": "2026-07-15T01:49:07.860970183Z",
  "published": "2026-07-08T20:47:09.051Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/libp2p/js-libp2p/releases/tag/gossipsub-v16.0.0"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/49xxx/CVE-2026-49866.json"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/libp2p/js-libp2p/security/advisories/GHSA-cwc9-cp4j-mcvv"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-49866"
    },
    {
      "type": "FIX",
      "url": "https://github.com/libp2p/js-libp2p/commit/773dd80ded24dbd6b19e675c89fd2f3b45f2d899"
    },
    {
      "type": "FIX",
      "url": "https://github.com/libp2p/js-libp2p/pull/3520"
    }
  ],
  "schema_version": "1.8.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
      "type": "CVSS_V3"
    }
  ],
  "summary": "libp2p: CPU DoS via oversized IHAVE and IWANT control message arrays"
}