CVE-2026-43678

Published Aug 20, 2026

Last updated 4 days ago

CVSS medium 5.3

Overview

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.
Source
product-security@apple.com
NVD status
Received

Risk scores

CVSS 3.1

Type
Secondary
Base score
5.3
Impact score
1.4
Exploitability score
3.9
Vector string
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
Severity
MEDIUM

Weaknesses

134c704f-9b21-4f2e-91b3-4a467353bcc0
CWE-20

Social media

Hype score
Not currently trending

References

Sources include official advisories and independent security research.