CVE-2026-43678CWE-20CWE-770denial-of-service

CVE-2026-43678

Medium · published August 20, 2026

CVSS v3.1
5.3
EPSS
0%
Percentile
30.2
In the wild
Unconfirmed
What it is

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.

The record
Technical detail
CVSS v3.1
5.3 · MEDIUM
Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
CVSS v4.0
Not supplied
EPSS
0.00374 · 30.2th percentile
Weaknesses
CWE-20 · Improper Input Validation; CWE-770 · Allocation of Resources Without Limits or Throttling
Published
2026-08-20T23:16Z
Affected products (1)
ProductVersionsFixed in
apple/swiftnio< 2.101.02.101.0
References (1)
https://github.com/apple/swift-nio/security/advisories/GHSA-qcc5-f287-vgmq · [email protected]
EPSS history
Timeline
  • 20 AUG 18:57Z
    An unauthenticated remote peer can crash any NIOWebSocket-based server (including Vapor and Hummingbird) with a single 11-byte frame sent after a completed…
    cvelistv5