How severe is CVE-2026-43678?

CVE-2026-43678 has a CVSS 3.x base score of 5.3, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability low.

Is CVE-2026-43678 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (29th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-43678?

CVE-2026-43678 affects Apple Swiftnio. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-43678?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

When was CVE-2026-43678 published?

CVE-2026-43678 was published on 2026-08-20 and last updated on 2026-08-28.

CVE-2026-43678

CVE-2026-43678 is a medium-severity vulnerability in Apple Swiftnio with a CVSS 3.x base score of 5.3. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-20.

Key facts

Severity: Medium (CVSS 3.x base score 5.3)
EPSS exploit prediction: 0% (29th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-20
Affected product: Apple Swiftnio
Published: 2026-08-20
Last modified: 2026-08-28

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.

Frequently asked questions

What is 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. This vulnerability is addressed in swift-nio version 2.101.0.
How severe is CVE-2026-43678?: CVE-2026-43678 has a CVSS 3.x base score of 5.3, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability low.
Is CVE-2026-43678 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (29th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-43678?: CVE-2026-43678 affects Apple Swiftnio. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-43678?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2026-43678 published?: CVE-2026-43678 was published on 2026-08-20 and last updated on 2026-08-28.

References

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

Affected products (1)

cpe:2.3:a:apple:swiftnio:*:*:*:*:*:*:*:*

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