{"id":"CVE-2026-49866","aliases":["GHSA-cwc9-cp4j-mcvv"],"url":"https://o3.security/vulnerability/CVE-2026-49866","summary":"libp2p: CPU DoS via oversized IHAVE and IWANT control message arrays","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.","published":"2026-07-08T20:47:09.051Z","modified":"2026-08-12T03:51:14.797761783Z","cvss":{"score":7.5,"severity":"HIGH","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"},"epss":{"score":0.00441,"percentile":0.36527,"asOf":"2026-08-14"},"cisaKev":null,"exploitsKnown":0,"affectedPackages":[{"ecosystem":"npm","name":"@libp2p/gossipsub","fixedVersion":"16.0.0"}],"fix":{"url":"https://github.com/libp2p/js-libp2p/commit/773dd80ded24dbd6b19e675c89fd2f3b45f2d899","label":"libp2p/js-libp2p@773dd80"},"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"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-08-12T03:51:14.797761783Z"}}