Vulnerability Description
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.
CVSS Score
HIGH
Related Weaknesses (CWE)
References
- https://github.com/libp2p/js-libp2p/commit/773dd80ded24dbd6b19e675c89fd2f3b45f2d
- https://github.com/libp2p/js-libp2p/pull/3520
- https://github.com/libp2p/js-libp2p/releases/tag/gossipsub-v16.0.0
- https://github.com/libp2p/js-libp2p/security/advisories/GHSA-cwc9-cp4j-mcvv
FAQ
What is CVE-2026-49866?
CVE-2026-49866 is a vulnerability with a CVSS score of 7.5 (HIGH). libp2p is a JavaScript Implementation of libp2p networking stack. Prior to 16.0.0, @libp2p/gossipsub defaultDecodeRpcLimits set maxIhaveMessageIDs and maxIwantMessageIDs to Infinity, allowing oversize...
How severe is CVE-2026-49866?
CVE-2026-49866 has been rated HIGH with a CVSS base score of 7.5/10. Review the CVSS metrics above for detailed severity breakdown.
Is there a patch for CVE-2026-49866?
Check the references section above for vendor advisories and patch information. Review vendor security bulletins for remediation guidance.