CVE-2026-43678

State: Published
Severity: 5.3 Medium
Published: Aug 20, 2026
Updated: Aug 20, 2026
Reserved: May 1, 2026

Description

An unauthenticated remote peer can crash any NIOWebSocket-based server (including Vapor and Hummingbird) with a single 11-byte frame sent after a completed WebSocket handshake, dropping all active connections until the process restarts. This vulnerability is addressed in swift-nio version 2.101.0.

Scores

CVSS	Score	Vector	Source
3.1	5.3 Medium	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L	CISA-ADP

Weaknesses

CWE-20 Improper Input Validation
CWE-770 Allocation of Resources Without Limits or Throttling

Affected Products

Product	Versions
swift-nioApple	before 2.101.0Affected

References

https://github.com/apple/swift-nio/security/advisories/GHSA-qcc5-f287-vgmq

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