CVE-2026-86966 in iOS
Summary
by MITRE • 10/26/2026
This issue was addressed with improved handling of symlinks. This issue is fixed in iOS 26.7.2 and iPadOS 26.7.2, iOS 27 and iPadOS 27, macOS Golden Gate 27, macOS Sequoia 15.8.2, macOS Tahoe 26.7.2, visionOS 27. An app may be able to modify protected parts of the file system.
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Analysis
by VulDB Data Team • 10/27/2026
The vulnerability described involves a flaw in how operating systems handle symbolic links within their file system security models. Symbolic links are special types of files that act as pointers or references to other files or directories, allowing for flexible path management and resource sharing. However, if the underlying implementation fails to properly validate these links before performing operations such as writes, deletions, or modifications, it can lead to a condition known as symlink following or race conditions where an application interacts with unintended targets. In this specific instance, the improved handling ensures that when an application attempts to modify files, the system correctly resolves and verifies the target of any symbolic link involved in the operation. This prevents scenarios where malicious code could exploit ambiguous path resolutions to bypass intended access controls.
The operational impact of this flaw is significant because it allows applications with standard permissions to potentially alter protected parts of the file system that should remain immutable or restricted to higher-privilege processes. By exploiting improper symlink handling, an attacker or compromised application can redirect write operations away from their intended destination and into sensitive system directories. This could result in the corruption of critical configuration files, the installation of unauthorized software components, or the modification of security-critical binaries. Such actions undermine the integrity of the operating environment and may facilitate further privilege escalation attacks where a low-privileged process gains control over high-security areas of the device.
This type of vulnerability is commonly categorized under CWE-59 Improper Link Resolution Before File Access, which highlights failures in validating symbolic links prior to performing file system operations. From an offensive security perspective, this aligns with ATT&CK techniques related to Defense Evasion and Privilege Escalation, specifically those involving path traversal or symlink manipulation to bypass access controls. The exploitation of such flaws often requires local execution privileges but can lead to substantial compromise of the device's trust boundary.
To mitigate these risks, it is essential to apply the provided updates immediately across all supported platforms including iOS 26.7.2 and iPadOS 26.7.2, as well as versions for macOS Golden Gate 27, Sequoia 15.8.2, Tahoe 26.7.2, and visionOS 27. These updates contain the necessary code changes to enforce stricter validation of symbolic links during file system interactions. Developers should also review their applications to ensure they do not rely on ambiguous path resolutions and instead use absolute paths or secure API calls that inherently prevent symlink abuse. Regular security audits focusing on file I/O operations can help identify similar patterns in custom software, ensuring compliance with modern operating system security standards.