CVE-2026-43820: 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. in Apple swift-nio-ssl
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.
AI Analysis
Technical Summary
The vulnerability in Apple swift-nio-ssl (CVE-2026-43820) arises because NIOSSLCertificate._subjectAlternativeNames accesses raw bytes of a certificate's SANs assuming the buffer is always backed by an ASN1_STRING. However, some SANs are not backed by ASN1_STRING, causing out-of-bounds memory access when the buffer is accessed. This is classified as a CWE-125 (Out-of-bounds Read) vulnerability. The issue is fixed in swift-nio-ssl version 2.37.2.
Potential Impact
Successful exploitation can result in out-of-bounds memory reads, potentially exposing sensitive information (confidentiality impact is high) and causing application crashes or denial of service (availability impact is high). Integrity impact is not affected. The vulnerability requires local access (AV:L) but no privileges or user interaction are needed.
Mitigation Recommendations
Upgrade swift-nio-ssl to version 2.37.2 or later, where this vulnerability is addressed. No other official remediation or temporary fixes are indicated. Patch status is confirmed by the vendor advisory stating the fix is in version 2.37.2.
CVE-2026-43820: 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. in Apple swift-nio-ssl
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.
CVSS v3.1
Score 7.7high
Affected software
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Weaknesses
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
The vulnerability in Apple swift-nio-ssl (CVE-2026-43820) arises because NIOSSLCertificate._subjectAlternativeNames accesses raw bytes of a certificate's SANs assuming the buffer is always backed by an ASN1_STRING. However, some SANs are not backed by ASN1_STRING, causing out-of-bounds memory access when the buffer is accessed. This is classified as a CWE-125 (Out-of-bounds Read) vulnerability. The issue is fixed in swift-nio-ssl version 2.37.2.
Potential Impact
Successful exploitation can result in out-of-bounds memory reads, potentially exposing sensitive information (confidentiality impact is high) and causing application crashes or denial of service (availability impact is high). Integrity impact is not affected. The vulnerability requires local access (AV:L) but no privileges or user interaction are needed.
Mitigation Recommendations
Upgrade swift-nio-ssl to version 2.37.2 or later, where this vulnerability is addressed. No other official remediation or temporary fixes are indicated. Patch status is confirmed by the vendor advisory stating the fix is in version 2.37.2.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- apple
- Date Reserved
- 2026-05-01T22:46:27.822Z
- Cvss Version
- null
- State
- PUBLISHED
- Remediation Level
- null
Threat ID: 6a622e759c2644c7f84289a4
Added to database: 07/23/2026, 15:08:37 UTC
Last enriched: 07/30/2026, 22:48:44 UTC
Last updated: 09/05/2026, 22:52:10 UTC
Views: 97
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