CVE-2021-30952: Apple Multiple Products Integer Overflow or Wraparound Vulnerability

Apple products including tvOS, macOS, Safari, iPadOS and watchOS contain an integer overflow or wraparound weakness that can be triggered by malicious web content. Successful exploitation may allow arbitrary code execution on the affected system. The issue matters because these products are widely deployed in enterprise and personal environments where web browsing is routine, creating a pathway for remote compromise without user interaction beyond visiting a crafted page.

How it works

The weakness is classified as CWE-190, an integer overflow or wraparound. In this class of flaw an arithmetic operation on an integer value exceeds the maximum or minimum representable value for its type, producing an incorrect result that the program then uses in memory operations.

An attacker supplies specially crafted web content that causes the vulnerable integer calculation to wrap. The resulting incorrect value can be leveraged to corrupt memory structures, ultimately allowing the attacker to redirect execution flow to attacker-controlled code. No specific exploit mechanics beyond the processing of malicious web content are documented in the available summary.

Am I affected? How to find it in your systems

Inventory all Apple-managed endpoints and browsers in the environment, focusing on devices running tvOS, macOS, iPadOS, watchOS and any deployment of Safari. Use existing device management tools or asset inventories to list installed operating system and browser versions, then compare those versions against the ranges listed in the vendor advisory.

• Examine network and endpoint telemetry for unexpected process crashes or memory corruption indicators in WebKit-based processes.
• Review web proxy or browser logs for access to domains or URLs previously associated with exploitation campaigns targeting similar integer-handling issues.
• Confirm the presence of any custom web content rendering paths that accept untrusted input and feed it directly into the affected components.

How to remediate

Apply the vendor-supplied update referenced in the official Apple security advisory as the primary remediation. After patching, review configurations that control web content handling and disable or restrict features that are not required for business operations.

• Enforce least-privilege execution contexts for browser and media processes where platform controls permit.
• Implement application allow-listing to limit which applications can render untrusted web content on managed devices.
• Validate that automatic update mechanisms are enabled and functioning for all listed Apple products.

If you can't patch immediately

Until patches can be deployed, reduce exposure by isolating systems that must process untrusted web content on separate network segments with strict egress controls. Consider virtual patching through web application firewalls or content-filtering proxies that can block or sanitize known malicious patterns associated with this vulnerability class.

• Disable JavaScript or other active content rendering in Safari where operationally feasible for high-risk user populations.
• Increase monitoring thresholds for anomalous memory or process behavior on unpatched endpoints and route those alerts to the security operations team.
• Follow any additional guidance in CISA BOD 22-01 for cloud-hosted instances of the affected products.

If your data may have been exposed

Actively exploited vulnerabilities of this type have led to unauthorized access and data exposure in other incidents. Organizations can run a free exposure scan of corporate email addresses against known breach datasets to determine whether related credentials or data have already appeared in public repositories.