Apple WebKit Integer Overflow (CVE-2021-30952)

Historical catalog analysis: CISA added this entry on March 05, 2026. The entry reflects catalog information retrieved on August 31, 2026, not a snapshot archived on the inclusion date. Check current vendor guidance before acting.

What the vulnerability is

CVE-2021-30952 is an integer overflow or wraparound vulnerability (CWE-190) located within the processing of web content. The flaw exists in how certain Apple products handle specifically crafted data, which could lead to arbitrary code execution on the target system.

Exposure and applicability

This vulnerability affects a broad range of Apple’s ecosystem due to shared components in the Safari browser engine. Affected systems include:
* macOS
* iPadOS
* tvOS
* watchOS
* Safari browser

Exposure occurs when a user interacts with maliciously crafted web content. Organizations maintaining fleets of Apple devices—particularly those used for corporate browsing or as endpoints in production environments—are the primary targets for this exposure.

Remediation priorities

Our analysis suggests prioritizing remediation based on the device’s exposure to untrusted web content. The following actions are recommended:

1. Deploy Vendor Patches: Prioritize updating macOS and iPadOS devices first, as these typically handle more diverse and untrusted web traffic than watchOS or tvOS.
2. Inventory Safari Versions: Identify all active installations of the Safari browser across the environment to ensure no legacy versions remain unpatched.
3. Cloud Service Review: For organizations utilizing Apple services in cloud environments, review configurations against BOD 22-01 guidance where applicable to reduce the attack surface.
4. Decommission Unsupported Assets: If a device cannot be updated to a version containing the fix, it should be discontinued or isolated from web access to eliminate the entry path.

How to validate remediation

Verification must move beyond simple version checks, as a deployed update does not always guarantee successful application across all partitions or user profiles.

Defenders should verify that the specific vendor-supplied mitigations linked in the advisory have been successfully applied. Validation is achieved by confirming the installation of the security updates specified in Apple’s support documentation for each respective OS. To ensure exposure reduction, vulnerability management teams should use authenticated scanning to confirm the presence of the patched binaries rather than relying on self-reported version strings from the OS.

Limits and open questions

While the vulnerability is documented as allowing arbitrary code execution, the source does not provide details on whether this requires user interaction (such as clicking a link) or if it can be triggered automatically upon page load. Additionally, while listed in the CISA Known Exploited Vulnerabilities catalog, the specific nature of active ransomware campaigns utilizing this flaw remains unknown.

Residual risk persists for devices that are functionally operational but cannot receive updates due to hardware age; in these cases, no software patch can eliminate the underlying integer overflow, and only complete isolation or replacement removes the risk.

Source and editorial note

CVE-2021-30952: Apple Multiple Products Integer Overflow or Wraparound Vulnerability · Source date: March 05, 2026 · Retrieved August 31, 2026.

Material facts are tied to the cited primary source. Recommendations are independent defensive analysis unless attributed to the source. Confirm consequential decisions against current authoritative guidance.

Archive date: March 08, 2026. The displayed post date is assigned three days after the source date to organize this retrospective archive; it does not mean this site published the analysis then. First published by this site: September 19, 2026 at 00:04 UTC.

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