Resource exhaustion in Libp2p Py-Libp2p
CVE-2026-73568
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.
Vulnerability class: DoS (Denial of Service)
Published · last modified .
CVSS v3 metric
CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.
EPSS exploit prediction
EPSS: 0.005 (39.5th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 40th percentile — 39.5% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.004 · newest: 0.005 · change: +0.001
Affected products
- Libp2p Py-Libp2p — versions <= 0.7.0
Weakness classification (CWE)
References
Frequently asked questions
- What is CVE-2026-73568?
- CVE-2026-73568 is a high-severity vulnerability in Libp2p Py-Libp2p, classified under Uncontrolled Resource Consumption. CVSS score: 7.5/10. Published 2026-08-13.
- How severe is CVE-2026-73568?
- High severity. CVSS v3 base score is 7.5 out of 10.