CVE-2026-73568: LIBP2P Py-LIBP2P

High severity, CVSS 7.5. EPSS: 0.5% chance of exploitation in the next 30 days.

py-libp2p is the Python implementation of the libp2p networking stack. In 0.7.0 and earlier, the yamux handle_incoming() method in libp2p/stream_muxer/yamux/yamux.py reads an attacker-controlled 32-bit DATA frame length with read_exactly() before validating it against MAX_WINDOW_SIZE or checking whether stream_id exists. A peer that completes the standard Noise handshake can send a 12-byte frame declaring a 0xFFFFFFFF body and then withhold the body, causing the sequential yamux read loop used by the default new_host() configuration to block and preventing every stream on that connection from making progress. No fixed version is available as of this review.

Affected products

• LIBP2P Py-LIBP2P: up to and including 0.7.0

Published 2026-08-13. Last modified 2026-09-18.