CVE-2021-1782: Apple iPadOS Privilege Escalation Flaw

CVE-2021-1782 Overview

CVE-2021-1782 is a race condition vulnerability affecting the kernel in multiple Apple operating systems. The flaw exists due to improper locking mechanisms within the kernel, which can be exploited by a malicious application to elevate privileges on affected devices. Apple has acknowledged that this vulnerability may have been actively exploited in the wild prior to the release of patches.

Critical Impact

This vulnerability allows a malicious application to gain elevated privileges on affected Apple devices. It has been confirmed as actively exploited in the wild and is listed in CISA's Known Exploited Vulnerabilities catalog.

Affected Products

• Apple iOS (versions prior to 14.4)
• Apple iPadOS (versions prior to 14.4)
• Apple macOS Big Sur (versions prior to 11.2)
• Apple macOS Catalina (prior to Security Update 2021-001)
• Apple macOS Mojave (prior to Security Update 2021-001)
• Apple tvOS (versions prior to 14.4)
• Apple watchOS (versions prior to 7.3)

Discovery Timeline

• April 2, 2021 - CVE-2021-1782 published to NVD
• October 23, 2025 - Last updated in NVD database

Technical Details for CVE-2021-1782

Vulnerability Analysis

This vulnerability is classified under CWE-667 (Improper Locking), which describes a flaw where a resource is improperly locked, leading to potential race conditions. In the context of CVE-2021-1782, the Apple kernel fails to properly synchronize access to shared resources, creating a timing window that can be exploited by an attacker.

Race conditions in kernel code are particularly dangerous because the kernel operates at the highest privilege level on the system. When an attacker successfully exploits such a timing vulnerability, they can manipulate kernel state during the race window to gain unauthorized elevated privileges.

Root Cause

The root cause of CVE-2021-1782 lies in insufficient locking mechanisms within the Apple kernel. When multiple threads or processes attempt to access shared kernel resources concurrently, the absence of proper synchronization primitives allows for a Time-of-Check Time-of-Use (TOCTOU) condition. This enables an attacker to modify data between the time it is validated and the time it is used, potentially corrupting kernel state or bypassing security checks.

Attack Vector

The attack vector for CVE-2021-1782 requires local access to the target device. An attacker must execute a malicious application on the affected system to trigger the race condition. The exploitation process typically involves:

1. The attacker installs or executes a malicious application on the target Apple device
2. The application creates multiple threads that simultaneously interact with vulnerable kernel interfaces
3. By carefully timing operations, the attacker triggers the race condition during a critical kernel operation
4. The improper locking allows the attacker to manipulate kernel memory or control flow
5. Successful exploitation results in privilege escalation from a standard user context to kernel-level privileges

Due to the nature of race condition exploitation, attacks may require multiple attempts to successfully hit the timing window. However, once achieved, the attacker gains complete control over the affected device.

Detection Methods for CVE-2021-1782

Indicators of Compromise

• Unexpected privilege escalation events in system logs
• Applications running with elevated privileges that should not have such access
• Kernel panic or system instability potentially related to race condition exploitation attempts
• Suspicious process behavior involving rapid thread creation and kernel system calls

Detection Strategies

• Monitor for applications exhibiting unusual patterns of kernel system calls, particularly those involving shared resource access
• Implement endpoint detection solutions capable of identifying privilege escalation attempts
• Enable comprehensive system logging to capture kernel-level events and anomalies
• Deploy behavioral analysis tools to detect exploitation attempts based on thread timing patterns

Monitoring Recommendations

• Review Apple Security Advisories and implement recommended security updates promptly
• Monitor CISA KEV catalog updates for emerging threat intelligence related to this vulnerability
• Utilize SentinelOne's Singularity platform for real-time detection of privilege escalation attempts on macOS and iOS devices
• Enable kernel extension monitoring on macOS systems to detect unauthorized modifications

How to Mitigate CVE-2021-1782

Immediate Actions Required

• Update all affected Apple devices to the patched versions immediately
• For iOS and iPadOS: Update to version 14.4 or later
• For macOS Big Sur: Update to version 11.2 or later
• For macOS Catalina and Mojave: Apply Security Update 2021-001
• For tvOS: Update to version 14.4 or later
• For watchOS: Update to version 7.3 or later

Patch Information

Apple has released patches addressing CVE-2021-1782 across all affected platforms. The vulnerability was fixed by implementing improved locking mechanisms in the kernel to properly synchronize access to shared resources. Detailed patch information is available through Apple's security advisories:

• Apple Support Article HT212146 - iOS 14.4 and iPadOS 14.4
• Apple Support Article HT212147 - macOS Big Sur 11.2
• Apple Support Article HT212148 - Security Update 2021-001 for Catalina and Mojave
• Apple Support Article HT212149 - watchOS 7.3

Additionally, this vulnerability is tracked in the CISA Known Exploited Vulnerabilities Catalog.

Workarounds

• Limit installation of applications to trusted sources only (App Store for iOS/iPadOS, verified developers for macOS)
• Restrict user privileges to the minimum necessary for daily operations
• Enable automatic updates to ensure timely patching of future vulnerabilities
• Implement mobile device management (MDM) solutions to enforce security policies across enterprise Apple devices

# Verify current macOS version to confirm patch status
sw_vers -productVersion

# Check for available software updates on macOS
softwareupdate --list

# Install all available security updates on macOS
softwareupdate --install --all