CVE-2026-112421 in macOS
Summary
by MITRE • 10/26/2026
A race condition was addressed with improved handling of symbolic links. This issue is fixed in macOS Golden Gate 27.2, macOS Sequoia 15.8.2, macOS Tahoe 26.7.2. An app may be able to modify protected parts of the file system.
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Analysis
by VulDB Data Team • 10/26/2026
The vulnerability described involves a race condition within the operating system's handling of symbolic links on macOS platforms including versions Golden Gate 27.2, Sequoia 15.8.2, and Tahoe 26.7.2. A race condition occurs when two or more processes access shared data concurrently, and the final outcome depends on the sequence in which the events take place. In this specific context, the flaw lies in how the system resolves symbolic links during file operations. Symbolic links are special files that act as pointers to other files or directories. When an application attempts to perform a write operation through such a link, there is a narrow window of time between when the system verifies the target location and when it actually executes the modification. If this timing check is not atomic, an attacker can exploit this gap by manipulating the symbolic link's target during execution. This technique allows malicious software to redirect file operations from intended safe locations to protected areas of the filesystem that are normally restricted for security reasons.
This technical flaw directly enables privilege escalation and unauthorized system modifications. By exploiting the race condition, a local application with limited permissions can bypass standard access controls designed to protect critical system directories or configuration files. The operational impact is significant because it compromises the integrity of the operating system's file structure. An attacker could overwrite essential binaries, inject malicious code into system processes, or alter security configurations that enforce sandboxing and isolation policies. This undermines the fundamental trust model of macOS where applications are expected to operate within confined environments without affecting core system components. The ability to modify protected parts of the filesystem can lead to persistent compromise, allowing attackers to maintain access even after reboots or apply further exploits with elevated privileges derived from the modified system files.
From a classification perspective, this vulnerability aligns closely with CWE-367 which defines Time-of-check to time-of-use (TOCTOU) race conditions. This category of flaws is particularly dangerous because they rely on precise timing rather than simple logic errors in code execution paths. In terms of the MITRE ATT&CK framework, this behavior corresponds to techniques involving file and directory permissions modification as well as defense evasion through manipulation of system resources. The exploitation method typically involves creating a symbolic link that points to a sensitive target and then rapidly swapping or modifying that link while the vulnerable process is attempting to write data. This requires local access initially but can serve as an initial foothold for more severe attacks if combined with other vulnerabilities or social engineering tactics to get code execution on the machine.
Mitigation strategies primarily involve applying the provided software updates which address the race condition by ensuring atomic operations during symbolic link resolution. System administrators and users should prioritize installing macOS Golden Gate 27.2, Sequoia 15.8.2, or Tahoe 26.7.2 immediately to close this security gap. Beyond patching, organizations can implement additional controls such as enforcing strict application sandboxing policies using tools like Apple's App Sandbox framework which restricts file system access by default. Monitoring for unusual patterns in symbolic link creation and modification within protected directories can also help detect potential exploitation attempts. Security teams should review their endpoint detection and response configurations to flag rapid successive file operations involving symlinks pointing to sensitive paths as high-risk events requiring immediate investigation.