CVE-2026-114213

CVE-2026-114213 · WebSocket 1-byte continuation frames bypass `max_fragmented_message_size` in Bandit

This page contains facts from public vulnerability sources. Check the original advisory before updating.

Allocation of Resources Without Limits or Throttling vulnerability in the WebSocket fragment reassembly of mtrudel bandit allows an unauthenticated remote attacker to exhaust server memory via a fragmented message made of many 1-byte continuation frames. Bandit.WebSocket.Connection checks max_fragmented_message_size against the payload bytes received, but keeps every non-final continuation frame as a new list cell around its own binary, and nothing limits the number of fragments. A 1-byte fragment costs 7 bytes on the wire but about 150 to 170 bytes of server memory, so one connection can hold about 150 times the configured limit, roughly 1.2 to 1.4 GB at the default 8 MB. Ping frames between fragments keep the connection alive past the idle timeout. This issue affects bandit: from 1.11.0 before 1.14.0.

CVSS 8.7 · High · EPSS 0.6% · Fix available

Published

2026-10-26T13:30:58.262Z

Updated

2026-10-26T15:35:51.785Z

Stack: system

Check your server →