CVE-2026-49866

libp2p: CPU DoS via oversized IHAVE and IWANT control message arrays

HIGH 7.5EPSS 0.6%

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.

Affected: libp2p · js-libp2p
CVSS v3.1 GITHUB: 7.5 HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
EPSS: 0.63% chance of exploitation in the next 30 days, 49th percentile
Published: 2026-07-08
Updated: 2026-07-09

Proof-of-concept exploits (1)

advisories/GHSA-cwc9-cp4j-mcvv

References

CVE Record
NVD entry