CVE-2026-49866: LIBP2P Js-LIBP2P

High severity, CVSS 7.5. EPSS: 0.6% chance of exploitation in the next 30 days.

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 products

• LIBP2P Js-LIBP2P: before 16.0.0 (fixed in 16.0.0)

Published 2026-07-08. Last modified 2026-07-10.