5.3

CVE-2026-43678: apple swift-nio Improper Input Validation

CVSS: 5.3v3.1MediumAnalyzed
Published 20-08-2026Last modified 20-08-2026
Open JSON

Vulnerability summary

CVE-2026-43678 is a medium (CVSS 5.3) Improper Input Validation vulnerability in apple swift-nio. EPSS estimates a 0.37% chance of exploitation in the next 30 days, higher than 29.9% of scored vulnerabilities.

Overall risk
21/100
0100
Low · default modelHow is this calculated?
CVSS score
5.3/10
010
Medium · v3.1 (CVE.org)
EPSS score
0.37%
0%100%
Low · +0.09 pp in 30 days
KEVNot listedIn no KEV catalog
RansomwareNone recordedNo known use recorded
Public exploits0No public exploits recorded

Timeline

  1. 20-08-2026
    PublishedVulnerability first disclosed.
  2. 20-08-2026
    Last modifiedVulnerability information updated.

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 metrics

2 scores · 2 sources · 1 version

EPSS trend

Probability

0.37%

Chance of exploitation in the next 30 days

Percentile

30%

Versus all other CVEs

30-day change

+0.09 pp

From 0.29% on 19-09-2026

19-09-202619-10-2026
EPSS score
0.37%

Known exploited

Compare KEV catalogs

Not in any of the 3 tracked catalogs.

Public exploits

0 found

No public exploits indexed.

Weaknesses

CWE · root cause

Affected systems

Apple2 products

1 vendor · 2 products

References

1 links