Vulnerability · Published Jul 23, 2026 · Assigned by apple
CVE-2026-43820
High 7.7
In plain English
A high-severity out-of-bounds read in swift-nio-ssl from Apple. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.1% (higher than 1% of all known vulnerabilities).
Severity (CVSS 3.1)7.7High
Exploit odds (30 days)0.1%top 98.8% of all CVEs
Exploited in the wildNo reportsCISA SSVC: poc
Attack toolingNoneno public tooling known
Official 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 (as reported)
| Vendor | Product | Versions |
|---|---|---|
| Apple | swift-nio-ssl | 0 – before 2.37.2 |
Weakness: CWE-125 · Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H