CVE-2019-8538 in macOS
Summary
by MITRE • 10/28/2020
A denial of service issue was addressed with improved validation. This issue is fixed in watchOS 5.2, macOS Mojave 10.14.4, Security Update 2019-002 High Sierra, Security Update 2019-002 Sierra, iOS 12.2. Processing a maliciously crafted vcf file may lead to a denial of service.
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Analysis
by VulDB Data Team • 05/04/2025
The vulnerability identified as CVE-2019-8538 represents a denial of service flaw that affects multiple Apple operating systems including watchOS, macOS, and iOS platforms. This issue stems from insufficient input validation mechanisms when processing vcf files, which are commonly used for contact information exchange in digital communications. The vulnerability was addressed through enhanced validation procedures implemented in security updates released by Apple in 2019.
The technical flaw manifests when a maliciously crafted vcf file is processed by affected Apple systems, leading to system instability and potential denial of service conditions. Vcf files, or vCard files, are standard formats for exchanging contact information between different applications and devices. The vulnerability exploits weaknesses in how these files are parsed and validated, allowing an attacker to construct specially formatted vcf content that triggers unexpected behavior in the processing applications. This type of vulnerability falls under CWE-20, which describes improper input validation, and represents a classic example of how malformed data can be leveraged to disrupt system operations.
The operational impact of CVE-2019-8538 extends beyond simple service disruption, as it can affect user productivity and system reliability across various Apple devices. When exploited, the vulnerability can cause applications to crash or become unresponsive, potentially requiring system restarts to restore normal functionality. This affects not only individual users but also enterprise environments where contact management systems are critical for business operations. The vulnerability's exploitation requires minimal user interaction, as simply opening or processing a malicious vcf file can trigger the denial of service condition, making it particularly concerning from a security perspective.
Mitigation strategies for CVE-2019-8538 primarily focus on applying the security updates released by Apple, which include watchOS 5.2, macOS Mojave 10.14.4, and the respective Security Updates 2019-002 for High Sierra and Sierra. These updates implement enhanced validation mechanisms that properly sanitize vcf file content before processing. Additionally, users should exercise caution when opening vcf files from untrusted sources and consider implementing email filtering solutions that can detect and quarantine potentially malicious contact data. From an ATT&CK framework perspective, this vulnerability aligns with techniques involving denial of service and privilege escalation through social engineering, though it does not require elevated privileges to exploit. Organizations should also consider implementing network-based intrusion detection systems that can monitor for unusual vcf file processing patterns and maintain regular patch management procedures to ensure all affected systems receive timely security updates.