CVE-2026-114213

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

HIGH
8.7
CVSS Score
Published: October 26, 2026 at 01:30 PM UTC
Updated: October 26, 2026 at 04:59 PM UTC
1 product affected across 1 vendorBandit

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Severity
HIGH8.7
Exploit prediction
EPSS 0.6%
SSVC
No known exploit

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

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

1.11.021612c7c7b1ce43eccd36d3af3a2299d23513667

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

SSVC — Action Prioritization

SSVCNo known exploitAutomatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

8.7HIGHEEF
Vector?

Quick Info

StatusAWAITING ANALYSIS
CWE
CWE-770

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