CVE-2026-43678
Low
No strong exploitation signal.
CVSS base
5.3
MEDIUM
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
EPSS — probability of exploitation (30 days)
0.3%
21.3th percentile
CISA KEV
Not listed
Weakness / dates
CWE-20
Published 2026-08-20 · modified 2026-08-28
CVSS breakdown
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
| Attack Vector | N | Network |
| Attack Complexity | L | Low |
| Privileges Required | N | None |
| User Interaction | N | None |
| Scope | U | Unchanged |
| Confidentiality | N | None |
| Integrity | N | None |
| Availability | L | Low |
Timeline
- 2026-08-20 — Published (NVD)
- 2026-08-28 — Last modified (NVD)
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.