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Vulnerability record · CVE-2026-49866 · published 8 July 2026

CVE-2026-49866: Allocation without limits vulnerability

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.

7.5 CVSS 3.1 High EPSS 0.63% · top 51.9% CWE-770 · Allocation without limits Deferred
7.5CVSS 3.1 base score
0.63%EPSS exploitation probability, 30 days
NoNot in CISA KEV
0Affected product versions listed by NVD
4References
10 Jul 2026Last modified by NVD

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

References

LinkTags
https://github.com/libp2p/js-libp2p/commit/773dd80ded24dbd6b19e675c89fd2f3b45f2d899
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

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Source: NIST National Vulnerability Database (record CVE-2026-49866), CISA KEV, FIRST EPSS (scores of 2026-09-27). This page is refreshed as NVD updates the record.