CVE-2021-31010: Apple iPadOS Privilege Escalation Flaw

CVE-2021-31010 Overview

CVE-2021-31010 is a critical deserialization vulnerability affecting multiple Apple operating systems that allows a sandboxed process to circumvent sandbox restrictions. This insecure deserialization flaw (CWE-502) stems from improper validation during object deserialization, enabling attackers to bypass security boundaries designed to isolate applications from sensitive system resources.

Apple acknowledged awareness that this vulnerability may have been actively exploited in the wild at the time of release, making this a high-priority security concern for organizations and individuals using affected Apple devices.

Critical Impact

A sandboxed process may be able to circumvent sandbox restrictions, allowing attackers to escape application isolation and potentially access sensitive system resources or execute unauthorized operations outside the sandbox boundary.

Affected Products

• Apple iOS (versions prior to 14.8 and 12.5.5)
• Apple iPadOS (versions prior to 14.8)
• Apple macOS Big Sur (versions prior to 11.6)
• Apple Mac OS X (Catalina - requires Security Update 2021-005)
• Apple watchOS (versions prior to 7.6.2)

Discovery Timeline

• August 24, 2021 - CVE-2021-31010 published to NVD
• October 23, 2025 - Last updated in NVD database

Technical Details for CVE-2021-31010

Vulnerability Analysis

This vulnerability exists within Apple's deserialization handling mechanisms across iOS, iPadOS, macOS, and watchOS platforms. The flaw allows processes running within the sandbox—a security mechanism designed to limit application access to system resources—to break out of these protective boundaries through malicious deserialization payloads.

The sandbox escape capability is particularly dangerous as Apple's sandbox architecture is a foundational security layer preventing applications from accessing files, services, and system components outside their designated scope. By circumventing these restrictions, an attacker could potentially access sensitive user data, interact with privileged system services, or chain this vulnerability with additional exploits for further system compromise.

This vulnerability was added to CISA's Known Exploited Vulnerabilities (KEV) catalog, indicating confirmed in-the-wild exploitation. The network-based attack vector combined with no required user interaction makes this vulnerability particularly concerning for enterprise environments.

Root Cause

The root cause of CVE-2021-31010 is improper validation during the deserialization of objects. When applications deserialize untrusted data without adequate validation, attackers can craft malicious serialized objects that, when processed, execute unintended operations. In this case, the insufficient validation allowed crafted payloads to manipulate sandbox restrictions, effectively granting processes capabilities beyond their intended permissions.

The CWE-502 (Deserialization of Untrusted Data) classification indicates that the system was accepting serialized data without proper integrity checks or type validation, allowing object instantiation that could manipulate sandbox state or bypass security checks.

Attack Vector

The vulnerability is exploitable via network-based attacks without requiring authentication or user interaction. An attacker could potentially deliver a malicious payload to a sandboxed application, which when deserialized, would allow the application to escape its sandbox constraints.

The attack flow typically involves:

1. Delivering a specially crafted serialized payload to a vulnerable sandboxed application
2. The application deserializes the malicious object without proper validation
3. The deserialization process manipulates sandbox state or exploits trust relationships
4. The sandboxed process gains access to resources outside its permitted scope

Due to the sensitive nature of this actively exploited vulnerability, specific exploitation code is not provided. Technical details are available through CISA's Known Exploited Vulnerabilities Catalog.

Detection Methods for CVE-2021-31010

Indicators of Compromise

• Unusual sandbox violation alerts or logs indicating processes accessing resources outside their permitted scope
• Unexpected inter-process communication from sandboxed applications to privileged system services
• Anomalous file access patterns from applications that should be confined to specific directories
• System logs showing deserialization errors or exceptions from sandboxed processes

Detection Strategies

• Monitor for sandbox escape attempts using Apple's unified logging system (log stream --predicate 'subsystem == "com.apple.sandbox"')
• Deploy endpoint detection solutions capable of identifying anomalous process behavior and sandbox violations
• Implement behavioral analysis to detect sandboxed applications accessing unexpected system resources
• Review application entitlements and compare runtime behavior against declared capabilities

Monitoring Recommendations

• Enable comprehensive logging for sandbox-related events across all Apple devices
• Configure SentinelOne agents to monitor for sandbox escape indicators and deserialization-related anomalies
• Establish baseline behavior profiles for critical applications to identify deviations indicative of exploitation
• Implement network monitoring to detect potential payload delivery attempts targeting vulnerable applications

How to Mitigate CVE-2021-31010

Immediate Actions Required

• Apply Apple security updates immediately: iOS 14.8, iPadOS 14.8, iOS 12.5.5, macOS Big Sur 11.6, Security Update 2021-005 Catalina, and watchOS 7.6.2
• Prioritize patching for devices in enterprise environments due to confirmed in-the-wild exploitation
• Conduct inventory of all Apple devices to identify systems running vulnerable versions
• Implement network segmentation to limit potential lateral movement from compromised devices

Patch Information

Apple has released security updates addressing this vulnerability across all affected platforms:

• iOS 14.8 and iPadOS 14.8 - HT212807
• iOS 12.5.5 - HT212824
• macOS Big Sur 11.6 - HT212804
• Security Update 2021-005 Catalina - HT212805
• watchOS 7.6.2 - HT212806

Organizations should prioritize deployment through MDM solutions for managed devices and communicate urgency to users with personal devices accessing corporate resources.

Workarounds

• Restrict application installations to vetted, trusted sources (App Store only) to reduce exposure to malicious payloads
• Implement network-level controls to limit exposure of vulnerable devices to untrusted content
• Enable application-level firewalls and review application network permissions
• Consider isolating unpatched devices from sensitive network resources until updates can be applied

# Verify macOS version and security updates
sw_vers
softwareupdate --history

# Check iOS/iPadOS version via command line (for supervised devices)
# Settings > General > About > Software Version should show 14.8 or later

# Force check for available updates on macOS
softwareupdate --list