CVE-2021-30876 Explained : Impact and Mitigation

An out-of-bounds read vulnerability has been identified and fixed in macOS versions prior to 12.0, macOS versions prior to 2021, and macOS Big Sur versions prior to 11.6. Exploiting this issue could lead to unexpected application termination or disclosure of process memory.

Understanding CVE-2021-30876

This CVE involves an out-of-bounds read vulnerability in macOS that could be exploited via a maliciously crafted AppleScript binary to cause application termination or memory leakage.

What is CVE-2021-30876?

CVE-2021-30876 is an out-of-bounds read vulnerability in macOS that allows for unexpected application termination or disclosure of process memory due to improper bounds checking.

The Impact of CVE-2021-30876

The impact of CVE-2021-30876 could be severe as attackers could leverage this vulnerability to disrupt application execution or access sensitive process memory.

Technical Details of CVE-2021-30876

This section provides a detailed overview of the vulnerability including its description, affected systems, and the exploitation mechanism.

Vulnerability Description

The vulnerability stems from an out-of-bounds read issue in macOS that lacks proper bounds checking, enabling attackers to craft malicious AppleScript binaries that trigger unexpected application behaviors.

Affected Systems and Versions

macOS versions prior to 12.0 (macOS Monterey)
macOS versions prior to 2021
macOS Big Sur versions prior to 11.6

Exploitation Mechanism

By processing a specially crafted AppleScript binary, threat actors can trigger the out-of-bounds read vulnerability, potentially leading to application crashes or exposure of sensitive process memory.

Mitigation and Prevention

To address CVE-2021-30876, users and organizations should take immediate action to mitigate the risk and implement long-term security practices.

Immediate Steps to Take

Update macOS to the latest version, which includes security patches addressing the vulnerability.
Avoid executing or opening unknown or untrusted AppleScript binaries or files.
Monitor vendor security advisories for any additional guidance or patches related to CVE-2021-30876.

Long-Term Security Practices

Regularly update and patch all software and operating systems to prevent known vulnerabilities.
Educate users on safe computing practices and the risks associated with executing untrusted scripts or binaries.

Patching and Updates

Ensure that all security updates, including macOS Monterey 12.0.1, Security Update 2021-007 Catalina, and macOS Big Sur 11.6.1, are applied promptly to mitigate the CVE-2021-30876 vulnerability.