CVE-2021-1764 in watchOS
Summary
by MITRE • 04/03/2021
A use after free issue was addressed with improved memory management. This issue is fixed in macOS Big Sur 11.2, Security Update 2021-001 Catalina, Security Update 2021-001 Mojave, watchOS 7.3, tvOS 14.4, iOS 14.4 and iPadOS 14.4. A remote attacker may be able to cause a denial of service.
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Analysis
by VulDB Data Team • 04/09/2021
This vulnerability represents a classic use after free condition that was resolved through enhanced memory management protocols in Apple's operating systems. The flaw occurred when a program attempted to access memory that had already been freed, creating potential exploitation vectors for malicious actors. The issue affected multiple Apple platforms including macOS Big Sur, iOS, watchOS, and tvOS, indicating a widespread memory management weakness that required coordinated patching across the entire ecosystem. Such vulnerabilities are particularly dangerous because they can be leveraged to execute arbitrary code or cause system instability.
The technical nature of this vulnerability aligns with CWE-416, which specifically addresses use after free conditions in software applications. This classification indicates that the flaw involved accessing memory after it had been deallocated by the program's memory management system. The vulnerability's remote exploitability means that attackers could potentially trigger the condition without physical access to the device, making it particularly concerning for enterprise and consumer environments. The memory management failure likely occurred during the handling of dynamic memory allocation operations where proper reference counting or object lifecycle management was insufficient.
The operational impact of this vulnerability extends beyond simple denial of service scenarios, as it represents a fundamental security weakness that could be escalated to more severe attacks. Remote attackers capable of triggering the use after free condition could potentially execute malicious code with the privileges of the affected application or system process. This risk is particularly significant in environments where users might interact with untrusted content or where the vulnerable applications handle sensitive data. The vulnerability's presence across multiple Apple platforms suggests that the underlying memory management flaw was systemic rather than isolated to a single component or service.
The mitigation strategy for this vulnerability required immediate deployment of Apple's security updates across all affected platforms. The patches implemented improved memory management protocols that prevent the reuse of freed memory blocks and enhance the validation of memory operations. Organizations should prioritize the deployment of these security updates, particularly in enterprise environments where the risk of exploitation is higher. The fix addresses the root cause by implementing proper memory lifecycle management and ensuring that object references are properly invalidated when memory is freed. This vulnerability demonstrates the critical importance of robust memory management practices in preventing exploitation vectors that can lead to complete system compromise.