CVE-2021-31010 is a sandbox bypass vulnerability in Apple iOS, macOS, watchOS. CISA added it to the Known Exploited Vulnerabilities catalogue on 25 August 2022, which means attackers have used it in real attacks. In affected versions of Apple iOS, macOS, and watchOS, a sandboxed process may be able to circumvent sandbox restrictions.
What the vulnerability is and why sandbox bypass matters
A sandbox bypass means a process can escape part of the restrictions meant to confine it. In Apple iOS, macOS and watchOS, that matters because the sandbox is a core containment boundary, so a bypass can let code do more than the platform intended.
On Apple devices, sandboxing is one of the main lines separating a compromised app or process from broader system access. When that boundary fails, the immediate concern is not just one app misbehaving, but the possibility that an attacker can move from a narrow foothold into wider access, stronger persistence, or additional exploitation steps.
What exposure typically needs to be checked
For an issue like this, organisations need to know which Apple endpoints they operate, where those systems are internet-facing or exposed through remote management, and whether the vulnerable product family is present in any high-trust workflow. Asset inventory is the starting point, because you cannot assess exposure if you do not know which devices and OS builds exist.
Vendor advisories and the official vulnerability record should be the source for version and patch details, while the KEV listing shows that this specific CVE has been used in real attacks. For canonical reference, use the CVE Program and the NIST National Vulnerability Database alongside Apple’s own security notes.
Remediation and compensating controls
The primary fix is to apply the relevant Apple security update as soon as operationally possible. Until that is done, reduce exposure by limiting which devices can reach sensitive services, constraining local execution paths, and tightening monitoring around endpoints that cannot be patched immediately.
Where patching must wait, compensating controls should focus on reducing the blast radius of any successful sandbox escape. That usually means restricting privileged local actions, limiting access to sensitive data and admin channels from affected devices, and treating the endpoint as potentially more permissive than normal until it is remediated.
Detection, validation, and compromise review
After remediation, organisations should still review logs and endpoint telemetry for signs that the weakness was exploited before patching. A sandbox bypass is often only one step in a broader intrusion chain, so the review should look for unusual process behaviour, suspicious child processes, unexpected data access, and follow-on activity that indicates the attacker used the bypass to advance further.
If exploitation is suspected, validate whether the device retained any persistence, configuration change, or secondary payload. The question is not only whether the CVE is patched, but whether the endpoint was already used as a stepping stone before the fix was applied.
Risk and Threat Considerations
This type of vulnerability is dangerous because it weakens a containment control that defenders often rely on to limit post-compromise damage. Even when the initial foothold is small, sandbox escape can convert a limited execution path into broader access, stronger persistence, or easier follow-on exploitation.
Failure mechanism: An attacker who lands code execution in a sandboxed context may abuse the bypass to evade intended restrictions, reach data or processes outside the sandbox boundary, and chain the access into deeper compromise.
Impact: The practical effect can be expanded device compromise, greater exposure of local data or credentials, and a better launch point for lateral movement or additional payloads.
Standards & Framework Alignment
This section maps relevant standards and security frameworks to the operational risks and controls described in this guidance.
MITRE ATT&CK addresses the attack and risk surface, while CIS Controls v8 and NIST SP 800-53 Rev 5 set the governance and control requirements practitioners need to meet.
| Framework | Control / Reference | Relevance |
|---|---|---|
| MITRE ATT&CK | T1611 — Escape to Host | Sandbox bypass directly maps to escaping a constrained execution boundary. |
| Recommendation — Map suspicious sandbox escapes to T1611 and hunt for follow-on privilege expansion on affected endpoints. | ||
| CIS Controls v8 | CIS-7 — Continuous Vulnerability Management | This CVE requires exposure discovery, prioritisation, and rapid remediation of affected Apple assets. |
| Recommendation — Track affected Apple endpoints under CIS-7 and verify patch status before closing exposure. | ||
| NIST SP 800-53 Rev 5 | SI-2 — Flaw Remediation | The vulnerability demands timely remediation and verification of security updates on affected systems. |
| SI-3 — Malicious Code Protection | A sandbox bypass can enable follow-on payload execution and requires stronger endpoint containment. | |
| AU-6 — Audit Review, Analysis, and Reporting | Post-patch review depends on log analysis to find pre-remediation compromise and follow-on abuse. | |
| Recommendation — Apply SI-2 to accelerate update deployment and confirm remediation on exposed Apple devices. Use SI-3 to increase endpoint protections and detect suspicious post-bypass activity. Use AU-6 to review endpoint telemetry for signs of exploitation and post-patch persistence. | ||