CVE-2026-43820

7.7 HIGH 0.1% exploit odds Fix listed Memory safety

What it is

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.

At a glance

Exploitability: Can be exploited locally on the machine without logging in. High risk of data exposure, service disruption.
Exploit odds: 0.1% chance of exploitation in the next 30 days (EPSS).
Fix: A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

2026-07-23 15:17 UTC PublishedDisclosed publicly on CVE.org and NVD
2026-10-24 13:10 UTC Last updatedMost recent change to the record

Why it ranks here

Exploited in the wild: no, CISA does not list it.
Exploit odds: 0.1% in the next 30 days (EPSS).
Severity: 7.7 HIGH (CVSS).
Fix: a patch or advisory is linked.

Details

Published: 2026-07-23 15:17 UTC
Last modified: 2026-10-24 13:10 UTC
Exploit probability: 0.1% · EPSS, next 30 days
Weakness: CWE-125 · Out-of-bounds read
Record status: Analyzed

Affected

Apple Swiftnio Ssl < 2.37.2

Attack profile CVSS 3.1 · 7.7

Attack vector: Local
Complexity: Low
Privileges needed: None
User interaction: None
Scope: Unchanged
Confidentiality: High
Integrity: None
Availability: High

Raw vector

CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H

Is it in your code?

Hand this to your coding agent. It searches your project for the affected products and checks versions. Nothing leaves your machine.

Read https://cve-list.com/agent/cve/CVE-2026-43820.md and follow it. Check whether this project is affected by CVE-2026-43820. Read only. Don't change anything and don't upload my code. Tell me yes, no or not sure, with the file as proof.

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Fix and advisories

References

NVD record · CVE.org record