CVE-2026-49866: CWE-770: Allocation of Resources Without Limits or Throttling in libp2p js-libp2p
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.
AI Analysis
Technical Summary
CVE-2026-49866 affects the js-libp2p JavaScript implementation of the libp2p networking stack. Before version 16.0.0, the defaultDecodeRpcLimits configuration set maxIhaveMessageIDs and maxIwantMessageIDs to Infinity. This allowed attackers to send oversized IHAVE and IWANT control message arrays, causing synchronous iteration over approximately 180,000 message IDs per 4 MB frame in message/decodeRpc.ts and gossipsub.ts. This synchronous processing blocks the Node.js event loop, resulting in a denial of service condition. The vulnerability is addressed by limiting these parameters in version 16.0.0.
Potential Impact
The vulnerability can cause a denial of service by blocking the Node.js event loop when processing large IHAVE and IWANT control message arrays. This impacts availability but does not affect confidentiality or integrity. There are no known exploits in the wild at this time.
Mitigation Recommendations
Upgrade js-libp2p to version 16.0.0 or later, where the issue is fixed by limiting maxIhaveMessageIDs and maxIwantMessageIDs to prevent unbounded resource allocation. No other mitigation is specified. Patch status is confirmed fixed in 16.0.0.
CVE-2026-49866: CWE-770: Allocation of Resources Without Limits or Throttling in libp2p js-libp2p
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 v3.1
Score 7.5high
Affected software
Weaknesses
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
CVE-2026-49866 affects the js-libp2p JavaScript implementation of the libp2p networking stack. Before version 16.0.0, the defaultDecodeRpcLimits configuration set maxIhaveMessageIDs and maxIwantMessageIDs to Infinity. This allowed attackers to send oversized IHAVE and IWANT control message arrays, causing synchronous iteration over approximately 180,000 message IDs per 4 MB frame in message/decodeRpc.ts and gossipsub.ts. This synchronous processing blocks the Node.js event loop, resulting in a denial of service condition. The vulnerability is addressed by limiting these parameters in version 16.0.0.
Potential Impact
The vulnerability can cause a denial of service by blocking the Node.js event loop when processing large IHAVE and IWANT control message arrays. This impacts availability but does not affect confidentiality or integrity. There are no known exploits in the wild at this time.
Mitigation Recommendations
Upgrade js-libp2p to version 16.0.0 or later, where the issue is fixed by limiting maxIhaveMessageIDs and maxIwantMessageIDs to prevent unbounded resource allocation. No other mitigation is specified. Patch status is confirmed fixed in 16.0.0.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- GitHub_M
- Date Reserved
- 2026-06-01T22:03:19.641Z
- Cvss Version
- 3.1
- State
- PUBLISHED
- Remediation Level
- null
Threat ID: 6a4ebdf5c9d9e3dbe3bf8afa
Added to database: 07/08/2026, 21:15:33 UTC
Last enriched: 07/16/2026, 10:04:24 UTC
Last updated: 08/22/2026, 10:52:09 UTC
Views: 109
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