CVE-2026-49866

HIGH 7.5

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

CVSS Score

7.5

EPSS Score

0.4%

EPSS Percentile

36th

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.

CWE	CWE-770
Vendor	libp2p
Product	js-libp2p
Published	Jul 8, 2026
Last Updated	Jul 9, 2026

Stay Ahead of the Next One

Get instant alerts for libp2p js-libp2p

Be the first to know when new high vulnerabilities affecting libp2p js-libp2p are published — delivered to Slack, Telegram or Discord.

Get Free Alerts → Free · No credit card · 60 sec setup

CVSS v3 Breakdown

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

None

Scope

Unchanged

Confidentiality

None

Integrity

None

Availability

High

Affected Versions

libp2p / js-libp2p

< 16.0.0

References

NVD ↗ CVE.org ↗ EPSS Data ↗

github.com: https://github.com/libp2p/js-libp2p/security/advisories/GHSA-cwc9-cp4j-mcvv github.com: https://github.com/libp2p/js-libp2p/pull/3520 github.com: https://github.com/libp2p/js-libp2p/commit/773dd80ded24dbd6b19e675c89fd2f3b45f2d899 github.com: https://github.com/libp2p/js-libp2p/releases/tag/gossipsub-v16.0.0