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CVE-2026-86040— libp2p: Unbounded RPC decode + synchronous subscription processing in @libp2p/floodsub allows unauthenticated DoS

Quick assessment

Affected
libp2p js-libp2p
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

libp2p 是 libp2p 网络栈的 JavaScript 实现。在 11.0.26 之前， 通过 （位于 ）在 端点接受未经身份验证的 RPC 帧，且未对 protobuf 元素施加限制。随后， 中的 和 函数同步处理 数组，且每帧没有设置数量上限。 一个尺寸受限的单帧可被解码为数百万个空的订阅条目，从而阻塞事件循环；而数十万个具有唯一主题的 SUBSCRIBE 条目则会在 中分配 对象，且在移除对等节点或停止时不会将这些对象移除。空条目会导致 CPU 耗尽，但不会导致 增长；要引发持续的内存增长，需要具有唯

CVSS 7.5 · High

Possible ATT&CK Techniques 1 AI

T1499 · Endpoint Denial of Service
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I. Basic Information for CVE-2026-86040

Vulnerability Information
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Vulnerability Title
libp2p: Unbounded RPC decode + synchronous subscription processing in @libp2p/floodsub allows unauthenticated DoS
Source: CVE Program / CVE List V5
Vulnerability Description
libp2p is a JavaScript implementation of the libp2p networking stack. Prior to 11.0.26, @libp2p/floodsub accepts unauthenticated RPC frames on /floodsub/1.0.0 through PeerStreams.attachInboundStream in packages/floodsub/src/peer-streams.ts without protobuf element limits, then processRpc and processRpcSubOpt in packages/floodsub/src/floodsub.ts synchronously process the subscriptions array without a per-frame cap. A single bounded-size frame can decode into millions of empty subscription entries that block the event loop, while hundreds of thousands of unique-topic SUBSCRIBE entries allocate PeerSet objects in this.topics that are not removed after peer removal or stop. Empty entries cause CPU exhaustion but do not grow this.topics; persistent memory growth requires unique topics. The subscription path bypasses message signature validation and the message-only processing queue, allowing a remote peer to cause sustained CPU denial of service, memory exhaustion, out-of-memory termination, and node unavailability. The issue is fixed in version 11.0.26.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Source: CVE Program / CVE List V5
Vulnerability Type
未加控制的资源消耗(资源穷尽)
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
libp2p js-libp2p < 11.0.26 -
@libp2p floodsub < 11.0.26 -

II. Public POCs for CVE-2026-86040

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III. Intelligence Information for CVE-2026-86040

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Patches & Fixes for CVE-2026-86040 (2)

Vendor Advisories for CVE-2026-86040 (1)

Vendor Pages for CVE-2026-86040 (1)

Same Patch Batch · libp2p · 2026-09-17 · 3 CVEs total

CVE-2026-86039 8.2 HIGH libp2p: PeerStore accepts attacker-signed PeerRecords for a victim peer ID and stores cert
CVE-2026-86038 7.5 HIGH libp2p: Gossipsub StrictSign accepts attacker-signed messages as a victim RSA peer ID

IV. Related Vulnerabilities

Same product: js-libp2p
Same vendor: libp2p
Same weakness: CWE-400

V. Comments for CVE-2026-86040

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