---
id: CVE-2026-73568
title: py-libp2p is the Python implementation of the libp2p networking stack
summary: >-
  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…
severity: high
cvss: 7.5
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H'
cwe:
  - CWE-400
vendor: libp2p
product: libp2p
affected:
  - libp2p <= 0.7.0
published: '2026-08-13'
updated: '2026-09-18'
sourceUpdated: '2026-09-18T20:09:01.757'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-73568'
references:
  - url: >-
      https://github.com/libp2p/py-libp2p/commit/146ea87d1a20cc7dacf684ecf7c204543be04b37
    label: security-advisories@github.com
  - url: >-
      https://github.com/libp2p/py-libp2p/security/advisories/GHSA-hmj8-5xmh-5573
    label: security-advisories@github.com
  - url: >-
      https://github.com/libp2p/py-libp2p/security/advisories/GHSA-hmj8-5xmh-5573
    label: 134c704f-9b21-4f2e-91b3-4a467353bcc0
  - url: 'https://github.com/libp2p/py-libp2p'
tags:
  - nvd
  - osv
  - pip
epss: 0.00488
epssPercentile: 0.39332
aliases:
  - GHSA-hmj8-5xmh-5573
ecosystem: pip
ingestedAt: '2026-08-13T19:18:20.712Z'
---

## Overview

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.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.

## Package advisory (CVE-2026-73568)

Affected packages:

- `libp2p <= 0.7.0`

Source: https://osv.dev/vulnerability/GHSA-hmj8-5xmh-5573