CVE-2021-31010
Apple iOS, macOS, watchOS Sandbox Bypass Vulnerability
Description
CVE-2021-31010 is a sandbox bypass vulnerability in Apple iOS, macOS, and watchOS that allows a sandboxed process to circumvent sandbox restrictions. The vulnerability undermines one of the most fundamental security mechanisms in Apple's operating systems, which isolates applications from each other and from critical system resources. By exploiting this flaw, malicious code running within a sandboxed application can escape its containment and access resources that should be restricted. CISA has added CVE-2021-31010 to its Known Exploited Vulnerabilities catalog, and with an EPSS score of 0.98% (77th percentile), targeted exploitation has been observed.
KEV Information
CVSS Score
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:NOpen in CalculatorAffected Products
| Vendor | Product | Version |
|---|---|---|
| apple | ipados | < 14.8 |
| apple | iphone os | >= 12.0, < 12.5.5; >= 14.0, < 14.8 |
| apple | mac os x | >= 10.15, < 10.15.7; 10.15.7 |
| apple | macos | >= 11.0, < 11.6 |
| apple | watchos | < 7.6.2 |
Multiple CVSS Assessments
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
References
- https://support.apple.com/en-us/HT212804(Vendor Advisory)
- https://support.apple.com/en-us/HT212805(Vendor Advisory)
- https://support.apple.com/en-us/HT212806(Vendor Advisory)
- https://support.apple.com/en-us/HT212807(Vendor Advisory)
- https://support.apple.com/en-us/HT212824(Vendor Advisory)
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-31010(US Government Resource)
Weakness Type
CWE-20: Improper Input Validation
CVE-2021-31010 exploits an improper input validation weakness in Apple's sandbox implementation across iOS, macOS, and watchOS. The sandbox enforcement mechanism fails to properly validate certain inputs or operations, allowing a sandboxed process to craft requests that bypass sandbox policy checks and gain access to resources outside its intended containment boundary.
Learn more: CWE-20 — Improper Input Validation
Impact Analysis
CVE-2021-31010 poses a significant threat to the security model of Apple devices. The vulnerability is exploitable locally from within a sandboxed application, requiring no user interaction beyond the initial installation or execution of the malicious application. While the sandbox bypass alone does not grant full system compromise, it is a critical enabler in exploit chains — when combined with other vulnerabilities such as code execution flaws, it allows attackers to escalate from limited application-level access to broader system-level access. This can result in unauthorized access to other applications' data, reading of protected system files and databases, bypassing of App Store security review protections, and enabling of further privilege escalation attacks. With an EPSS score of 0.98% (77th percentile), exploitation is observed in targeted attack campaigns rather than mass exploitation.
Exploit Maturity
CISA has confirmed active exploitation of CVE-2021-31010 in the wild by adding it to the Known Exploited Vulnerabilities catalog with a remediation deadline of September 15, 2022. The EPSS score of 0.98% (77th percentile) indicates moderate exploitation probability, consistent with its use in targeted attack campaigns rather than broad exploitation. Sandbox bypass vulnerabilities are particularly valuable in exploit chains targeting Apple devices, as they are typically combined with separate code execution vulnerabilities to achieve full device compromise. No specific ransomware campaigns are currently associated with this CVE.
Remediation
- Apply Apple security updates immediately: Per the CISA KEV required action, apply updates per vendor instructions. Update to iOS 14.8, iPadOS 14.8, macOS Big Sur 11.6, Security Update 2021-005 for Catalina, and watchOS 7.6.2 or later as documented in Apple security advisories HT212804-HT212807 and HT212824.
- Enable automatic security updates on all Apple devices: Configure devices to automatically install security updates to minimize exposure to future sandbox escape and other critical vulnerabilities.
- Limit application installation to trusted sources: Restrict application installation to the App Store and authorized enterprise distribution channels to reduce the risk of installing malicious applications that could exploit this vulnerability.
- Deploy mobile device management (MDM) controls: Implement MDM policies to enforce security configurations, monitor for signs of exploitation, and restrict capabilities of managed devices.
- Monitor for exploit chain indicators: Watch for signs of multi-stage exploitation on Apple devices, including unusual application behavior, unexpected process creation, or access to protected resources from sandboxed applications.
Technical Details
CVE-2021-31010 is a sandbox bypass vulnerability affecting Apple's sandbox implementation in iOS, macOS, and watchOS. Apple's sandbox mechanism uses a policy-based access control system that restricts what resources (files, network, hardware) each application can access. The vulnerability exists in the validation logic that enforces these policies, where certain inputs or system calls are not properly checked against the sandbox rules. A sandboxed process can exploit this gap to perform operations that should be denied by the sandbox policy, effectively escaping its containment boundary. This type of vulnerability is commonly used as one component in multi-stage exploit chains: an initial code execution vulnerability provides the attacker with code running inside a sandboxed application, and the sandbox bypass then allows that code to access restricted resources needed for further exploitation. Apple addressed the vulnerability in iOS 14.8, macOS Big Sur 11.6, and watchOS 7.6.2 by improving the validation logic in the sandbox enforcement code.
Frequently Asked Questions
Is CVE-2021-31010 being actively exploited?
Yes. CISA has added CVE-2021-31010 to its Known Exploited Vulnerabilities catalog, confirming active exploitation in the wild. The EPSS score of 0.98% (77th percentile) indicates targeted exploitation. The vulnerability is used as a component in exploit chains against Apple devices.
What products are affected by CVE-2021-31010?
CVE-2021-31010 affects Apple iOS (before 14.8), iPadOS (before 14.8), macOS (before Big Sur 11.6 and Security Update 2021-005 Catalina), and watchOS (before 7.6.2). All Apple devices running these older versions are vulnerable.
How do I fix CVE-2021-31010?
Update all Apple devices to iOS 14.8, iPadOS 14.8, macOS Big Sur 11.6 (or Security Update 2021-005 for Catalina), and watchOS 7.6.2 or later. Enable automatic security updates on all managed devices to ensure rapid deployment of future patches.
How severe is CVE-2021-31010?
CVE-2021-31010 is a significant sandbox bypass vulnerability that undermines Apple's core security isolation mechanism. While it does not directly enable code execution on its own, it is a critical component in exploit chains that achieve full device compromise. The EPSS score of 0.98% (77th percentile) and confirmed active exploitation make it a high-priority patching target.
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