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CVE-2026-43820

7.7 · HIGH

NIOSSLCertificate._subjectAlternativeNames provides access to the raw bytes for a cert's SANs.

Published Jul 23, 2026appleCWE-125EPSS 0.11%

Overview

CVE-2026-43820 is a high-severity vulnerability affecting apple swiftnio_ssl. It was published on July 23, 2026 and has a CVSS 3.1 base score of 7.7 (HIGH).

This vulnerability has a CVSS 3.1 base score of 7.7, rated HIGH. It requires local or adjacent network access to exploit. No authentication or special privileges are required for exploitation.

Technical description

NIOSSLCertificate._subjectAlternativeNames provides access to the raw bytes for a cert's SANs. NIOSSL provides access to a buffer assumed to be backed by an ASN1_STRING, but not all SANs are backed by ASN1_STRING, so accessing the buffer for such a type can lead to out-of-bounds memory access. This vulnerability is addressed in swift-nio-ssl version 2.37.2.

Remediation

Check the references section for vendor advisories and patches from apple. Update swiftnio_ssl to the latest patched version. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

Affected products

VendorProductVersionsStatus
appleswiftnio_ssl>= 2.18.0, < 2.37.2Affected

References

GitHubgithub.com/apple/swift-nio-ssl/security/advisories/GHSA-xfxg-9975-pc2jGitHubgithub.com/apple/swift-nio-ssl/security/advisories/GHSA-xfxg-9975-pc2j

How CyberStrike helps

Frequently asked questions

What is CVE-2026-43820?

CVE-2026-43820 is a high-severity vulnerability affecting apple swiftnio_ssl. It was published on July 23, 2026 and has a CVSS 3.1 base score of 7.7 (HIGH).

How severe is CVE-2026-43820?

This vulnerability has a CVSS 3.1 base score of 7.7, rated HIGH. It requires local or adjacent network access to exploit. No authentication or special privileges are required for exploitation.

How do I fix or remediate CVE-2026-43820?

Check the references section for vendor advisories and patches from apple. Update swiftnio_ssl to the latest patched version. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

How can CyberStrike help with CVE-2026-43820?

CyberStrike is an open-source, AI-augmented pentesting engine. Rather than flag a version number, it tests whether an issue like CVE-2026-43820 is actually reachable in your own applications and APIs, then verifies each finding before reporting it. That tells you if the weakness is a real, exploitable risk in your environment or a false positive you can safely deprioritize.

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