CVE-2026-49866Public exploitNetwork attack vectorHinoki check available

Remote service hang via unbounded control-message iteration

Published Jul 8, 2026 · Updated Jul 8, 2026

Resource consumption in @libp2p/gossipsub before 16.0.0 allows remote attackers to hang Node.js peers with oversized control messages. defaultDecodeRpcLimits leaves maxIhaveMessageIDs and maxIwantMessageIDs infinite, so handlers synchronously iterate every attacker-supplied ID before truncation or without rate limiting. Default-configured nodes accepting inbound connections are exposed; one IWANT peer or about ten IHAVE peers can prevent forwarding, heartbeats, and peer responses.

CVSS severity7.5
High
EPSS probability0.63%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkAvailable
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Summary

What happened

Resource consumption in @libp2p/gossipsub before 16.0.0 allows remote attackers to hang Node.js peers with oversized control messages. defaultDecodeRpcLimits leaves maxIhaveMessageIDs and maxIwantMessageIDs infinite, so handlers synchronously iterate every attacker-supplied ID before truncation or without rate limiting. Default-configured nodes accepting inbound connections are exposed; one IWANT peer or about ten IHAVE peers can prevent forwarding, heartbeats, and peer responses.

The record

CVE
CVE-2026-49866
Published
Jul 8, 2026
Updated
Jul 8, 2026
Vendor
libp2p
Product
js-libp2p
Classifications
CWE-20, CWE-400, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jul 8, 2026CVE publishedPublication date reported by the CVE source.
  2. Jul 8, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=< 16.0.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

libp2p · js-libp2pversion=< 16.0.0

Published CVSS scores

7.5GitHub Security AdvisoryCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-20Improper Input Validation
CWE-400Uncontrolled Resource Consumption
T1499.004Application or System Exploitation

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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