TI-2026-31770 Aliases CVE-2026-43678

Improper input validation in Apple swift-nio

LOW 30CWE-20Published 2026-08-20 · Updated 2026-08-20

Key facts

Attack vector: Network
Privileges required: None
User interaction: None
Attack complexity: Low
Impact type: Denial of service
Confidentiality · integrity · availability: None · None · Low
Fix status: Fixed

Attack profile from CVSS 3.1 · CISA ADP. Fix status from CNA. Impact type from CWE-770.

Summary

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.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV

EPSS 0.00374 31st percentileScored 2026-11-07

Fix Fixed swift-nio (Apple): 2.101.0

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation: None
Automatable: Yes
Technical impact: Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

Vendor	Product	Affected versions	Fixed in	Status	Source
Apple	swift-nio	before 2.101.0	2.101.0	Patch available	CNA

swift-nio VendorApple Affected before 2.101.0 Fixed in 2.101.0 Patch available CNA

CPE configurations NVD · 1

CPE	Versions	Role	Vendor
cpe:2.3:a:apple:swiftnio::::::::	before 2.101.0	Vulnerable	Apple

cpe:2.3:a:apple:swiftnio:*:*:*:*:*:*:*:* Versions before 2.101.0 Vulnerable ·Apple

Remediation

Fix · CNA swift-nio (Apple) Fixed in 2.101.0

Vendor assessments

Red Hat

Red Hat rating: Important. Red Hat's page for this CVE →

Not affected: 1 product

Red Hat Hardened Images

Timeline

2026-10-02 Threatist record created from CVE-2026-43678

References

Advisory 1

https://github.com/apple/swift-nio/security/advisories/GHSA-qcc5-f287-vgmq

TI-2019-06950 Some HTTP/2 implementations are vulnerable to a settings flood, potentially leading to a… CVSS 3.1HIGH 7.5
TI-2019-06949 Some HTTP/2 implementations are vulnerable to a reset flood, potentially leading to a… CVSS 3.1HIGH 7.5
TI-2019-06947 Some HTTP/2 implementations are vulnerable to ping floods, potentially leading to a… CVSS 3.1HIGH 7.5
TI-2019-06948 Some HTTP/2 implementations are vulnerable to resource loops, potentially leading to a… CVSS 3.1HIGH 7.5
TI-2019-06946 Some HTTP/2 implementations are vulnerable to window size manipulation and stream… CVSS 3.1HIGH 7.5
TI-2019-06951 Some HTTP/2 implementations are vulnerable to a header leak, potentially leading to a… CVSS 3.1MEDIUM 6.5

See all 10 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences