CVE-2026-43678: An unauthenticated remote peer can crash any NIOWebSocket-based server (including Vapor and Hummingbird) with a single 11-byte frame sent after a completed…

PriorityP432medium5.3CVSS 3.1

AVNACLPRNUINSUCNINAL

EPSS

0.29%

20.8th percentile

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.

Affected

2 ranges

Vendor	Product	Version range	Fixed in
apple	swift-nio	< 2.101.0	2.101.0
apple	swiftnio	< 2.101.0	2.101.0

CVSS provenance

nvdv3.15.3MEDIUMCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

vendor_redhat5.3MEDIUM

Stop checking back — get the weekly exploitation signal.

Every Monday: what got weaponized or added to CISA KEV in the last seven days — each CVE cross-linked to its PoC, Nuclei template, and detection rule. Free, one email a week, unsubscribe in one click.