CVE-2026-86039: libp2p js-libp2p Authentication Bypass by Spoofing

Vulnerability summary

CVE-2026-86039 is a high (CVSS 8.2) Authentication Bypass by Spoofing vulnerability in libp2p js-libp2p. EPSS estimates a 0.27% chance of exploitation in the next 30 days, higher than 17.9% of scored vulnerabilities.

Timeline

1. 17-09-2026
   PublishedVulnerability first disclosed.
2. 21-09-2026
   Last modifiedVulnerability information updated.

Description

libp2p is a JavaScript implementation of the libp2p networking stack. From 8.0.0 until 12.0.24, @libp2p/peer-store in packages/peer-store/src/index.ts uses consumePeerRecord to verify a RecordEnvelope signature but does not require PeerRecord.peerId in the signed payload to equal the signer peer ID derived by RecordEnvelope.openAndCertify. The expectedPeer option checks only the envelope signer, and the gossipsub Peer Exchange path can provide the attacker's own peer ID as expectedPeer. An attacker can therefore sign a record with the attacker's key, place a victim peer ID and attacker-controlled multiaddrs in the payload, and have certified addresses stored for the victim. The poisoned addresses can cause address-book corruption, dial redirection or failure, routing manipulation, and reachability disruption, although the connection upgrade still verifies remote peer identity and prevents a complete identity takeover. The issue is fixed in version 12.0.24.

• CWE-290Authentication Bypass by SpoofingThis attack-focused weakness is caused by incorrectly implemented authentication schemes that are subject to spoofing attacks.
• CWE-345Insufficient Verification of Data AuthenticityThe product does not sufficiently verify the origin or authenticity of data, in a way that causes it to accept invalid data.