What’s Vulnerable › Vulnerabilities

CVE-2026-43820

• Severity: high (CVSS 7.7 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.1% probability of exploitation in the next 30 days
• Public exploit or detection template: yes
• Published: 2026-07-23 · updated 2026-10-24
• Weakness: CWE-125

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.

Affected products

• Apple swift-nio-ssl: from 2.18.0 before 2.37.2 — fixed in 2.37.2

How to fix

Upgrade to a fixed version: Apple swift-nio-ssl 2.37.2. Check the vendor advisory for mitigations.

References

• https://github.com/apple/swift-nio-ssl/security/advisories/GHSA-xfxg-9975-pc2j
• https://github.com/apple/swift-nio-ssl/security/advisories/GHSA-xfxg-9975-pc2j

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