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 WebSocket handshake, dropping all active connections until the process restarts. in Apple swift-nio
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.
AI Analysis
Technical Summary
This vulnerability allows an unauthenticated remote attacker to crash any server using NIOWebSocket (including frameworks like Vapor and Hummingbird) by sending a crafted 11-byte frame after the WebSocket handshake completes. The crash results in the termination of the server process, dropping all active connections until the process is restarted. The flaw is addressed in swift-nio version 2.101.0.
Potential Impact
Successful exploitation results in a denial-of-service condition by crashing the server process and dropping all active WebSocket connections. This disrupts availability of services relying on NIOWebSocket-based servers until the server is manually or automatically restarted.
Mitigation Recommendations
Upgrade swift-nio to version 2.101.0 or later, where this vulnerability has been fixed. No other mitigation or temporary workaround is indicated.
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 WebSocket handshake, dropping all active connections until the process restarts. in Apple swift-nio
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.
CVSS v3.1
Score 5.3medium
Affected software
Run on your own infrastructure? Check whether these packages are installed with threat-finder — our free open-source scanner.
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
This vulnerability allows an unauthenticated remote attacker to crash any server using NIOWebSocket (including frameworks like Vapor and Hummingbird) by sending a crafted 11-byte frame after the WebSocket handshake completes. The crash results in the termination of the server process, dropping all active connections until the process is restarted. The flaw is addressed in swift-nio version 2.101.0.
Potential Impact
Successful exploitation results in a denial-of-service condition by crashing the server process and dropping all active WebSocket connections. This disrupts availability of services relying on NIOWebSocket-based servers until the server is manually or automatically restarted.
Mitigation Recommendations
Upgrade swift-nio to version 2.101.0 or later, where this vulnerability has been fixed. No other mitigation or temporary workaround is indicated.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- apple
- Date Reserved
- 2026-05-01T22:46:21.641Z
- Cvss Version
- null
- State
- PUBLISHED
- Remediation Level
- null
Threat ID: 6a8750b5acd9273b490631ed
Added to database: 08/20/2026, 19:08:37 UTC
Last enriched: 08/20/2026, 19:22:53 UTC
Last updated: 08/20/2026, 23:01:05 UTC
Views: 6
Community Reviews
0 reviewsCrowdsource mitigation strategies, share intel context, and vote on the most helpful responses. Sign in to add your voice and help keep defenders ahead.
Want to contribute mitigation steps or threat intel context? Sign in or create an account to join the community discussion.
Actions
Updates to AI analysis require Pro Console access. Upgrade inside Console → Billing.
Need more coverage?
Upgrade to Pro Console for AI refresh and higher limits.
For incident response and remediation, OffSeq services can help resolve threats faster.
Latest Threats
Check if your credentials are on the dark web
Instant breach scanning across billions of leaked records. Free tier available.