Allocation of Resources Without Limits or Throttling in Python Engine.IO - #VU132251
Published: May 25, 2026
Vulnerability identifier: #VU132251
CSH Severity: Medium
CVSS v4.0: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U/U:Green
CVE-ID: N/A
CWE-ID: CWE-770
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vendor: Miguel Grinberg
Affected software:
Python Engine.IO
Python Engine.IO
Detailed vulnerability description
The vulnerability allows a remote attacker to cause a denial of service.
The vulnerability exists due to allocation of resources without limits or throttling in the python-engineio server when handling POST requests with ASGI long polling or WebSocket messages with Aiohttp WebSocket transport. A remote attacker can send oversized messages to cause a denial of service.
The issue occurs only in two specific server configurations: ASGI with the long polling transport, and Aiohttp with the WebSocket transport.
Remediation
Install security update from vendor's website.