CVE-2026-43820

HIGH
7.7
CVSS Score
Published: July 23, 2026 at 02:33 PM UTC
Updated: October 24, 2026 at 01:10 PM UTC
1 product affected across 1 vendorSwiftnio SSL

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Severity
HIGH7.7
Exploit prediction
EPSS 0.1%
SSVC
PoC

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

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

2.18.0 ≤ v < 2.37.2
Affected range stops below 2.37.2, so it looks safe — our inference, not a vendor statement

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

References (1)

SSVC — Action Prioritization

SSVCPoCNot automatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

7.7HIGHCISA-ADP
Attack Vector
LOCAL
Complexity
LOW
Privileges
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
HIGH
Integrity
NONE
Availability
HIGH
Vector?

Quick Info

StatusANALYZED
CWE
CWE-125

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