CVE-2026-43678

EUVD-2026-63577
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.
ProviderTypeBase ScoreAtk. VectorAtk. ComplexityPriv. RequiredVector
NISTPrimary
5.3 MEDIUM
NETWORK
LOW
NONE
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
Base Score
CVSS 3.x
EPSS Score
Percentile: 29.07%
Affected Products (NVD)
VendorProductVersion
appleswiftnio
𝑥
< 2.101.0
𝑥
= Vulnerable software versions
Common Weakness Enumeration
References
https://github.com/apple/swift-nio/security/advisories/GHSA-qcc5-f287-vgmq