CVE-2020-9926 in iCloud
Summary
by MITRE • 04/03/2021
A use after free issue was addressed with improved memory management. This issue is fixed in iOS 13.6 and iPadOS 13.6, tvOS 13.4.8, watchOS 6.2.8, iCloud for Windows 7.20, macOS Catalina 10.15.6, Security Update 2020-004 Mojave, Security Update 2020-004 High Sierra. Processing maliciously crafted XML may lead to an unexpected application termination or arbitrary code execution.
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Analysis
by VulDB Data Team • 04/08/2021
The vulnerability described in CVE-2020-9926 represents a critical use-after-free condition that emerged in Apple's software ecosystem affecting multiple platforms including iOS, iPadOS, tvOS, watchOS, and macOS operating systems. This type of memory corruption flaw occurs when an application attempts to access memory that has already been freed or deallocated, creating potential entry points for malicious exploitation. The vulnerability specifically manifests during the processing of maliciously crafted xml data structures, which triggers improper memory management handling within the affected software components. Such issues fall under the common weakness enumeration CWE-416 which categorizes use-after-free vulnerabilities as a fundamental memory safety problem that can lead to system instability and potential code execution. The security implications of this flaw extend across Apple's ecosystem as the same underlying memory management issue affects multiple operating system versions and device types.
The technical exploitation of this vulnerability requires an attacker to craft specially designed xml content that, when processed by the affected applications, triggers the use-after-free condition. This typically involves manipulating xml parsers or processing libraries that handle xml data structures, causing the application to free memory associated with xml elements while still maintaining references to that memory location. When the application attempts to access this freed memory, it can result in unpredictable behavior ranging from application crashes to complete system compromise. The flaw's impact is particularly concerning because xml processing is a common operation in web applications, document handling, and data exchange scenarios, making it a realistic attack vector for various threat actors. The vulnerability's classification aligns with attack techniques documented in the attack tree framework under techniques related to memory corruption exploits and privilege escalation through application flaws.
The operational impact of CVE-2020-9926 extends beyond simple application instability to potentially enable arbitrary code execution on compromised systems. When exploited successfully, this vulnerability could allow attackers to execute malicious code with the privileges of the affected application, potentially leading to full system compromise. The affected platforms include critical consumer devices such as iphones, ipads, apple tvs, and apple watches, which are frequently targeted by threat actors due to their widespread use and the valuable data they contain. The vulnerability affects not only mobile platforms but also desktop operating systems including macos catalina, mojave, and high sierra, demonstrating the cross-platform nature of the memory management issue. Organizations and individuals using affected versions of these operating systems face significant risk as the exploitation could lead to data theft, unauthorized access, and persistent system compromise.
Apple's remediation approach for this vulnerability involved implementing improved memory management protocols specifically targeting the xml processing components that were susceptible to the use-after-free condition. The security updates released for iOS 13.6, iPadOS 13.6, tvOS 13.4.8, watchOS 6.2.8, and the corresponding macOS security updates addressed the underlying memory handling flaws by ensuring proper memory deallocation and reference management during xml processing operations. The mitigation strategy aligns with industry best practices for preventing memory corruption vulnerabilities and follows established security frameworks for software hardening. Organizations should prioritize immediate deployment of these security updates across all affected systems, as the vulnerability's exploitation potential makes it a high-priority target for cybercriminals. The fix demonstrates Apple's commitment to addressing memory safety issues through proactive security measures and proper software development lifecycle practices that prevent similar vulnerabilities from emerging in future releases.