Remote Downtime Vulnerability in NIOWebSocket Servers by Apple
CVE-2026-43678

5.3MEDIUM

Key Information:

Vendor

Apple
Status
Swift-nio
Vendor
CVE Published:
20 August 2026

What is CVE-2026-43678?

A remote peer can exploit a vulnerability in NIOWebSocket-based servers such as Vapor and Hummingbird by sending a specific 11-byte frame after the WebSocket handshake. This can lead to a denial of service, causing all active connections to drop until the server process is restarted. The issue is resolved in swift-nio version 2.101.0.

Affected Version(s)

swift-nio 0 < 2.101.0

References

https://github.com/apple/container/security/advisories/GH...

CVSS V3.1

Score:
5.3
Severity:
MEDIUM
Confidentiality:
None
Integrity:
None
Availability:
None
Attack Vector:
Network
Attack Complexity:
Low
Privileges Required:
None
User Interaction:
None
Scope:
Unchanged

Timeline

  • Vulnerability published

  • Vulnerability Reserved

.