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CVE PROGRAM SOURCE RECORD8.7 High

CVE-2026-114213

WebSocket 1-byte continuation frames bypass `max_fragmented_message_size` in Bandit

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Status
Published
Published
Updated
Assigning organization
EEF

Description

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.

Affected products

Version statuses are supplied by the assigning organization. Consult the original record for detailed ranges and platform conditions.

mtrudel bandit

Default version status: unaffected

  • 1.11.0 to < 1.14.0affected
pkg:hex/bandit

mtrudel bandit

Default version status: unaffected

  • 21612c7c7b1ce43eccd36d3af3a2299d23513667 to < 220b9dfd27f9a21305be2afc75cbe585ddc24e7aaffected
pkg:github/mtrudel/bandit

References