CVE-2026-86886 in iOS
Summary
by MITRE • 09/15/2026
A path traversal issue was addressed with improved input validation. This issue is fixed in iOS 26.7 and iPadOS 26.7, iOS 27 and iPadOS 27, watchOS 27. An app may be able to modify protected system files.
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Analysis
by VulDB Data Team • 09/15/2026
The vulnerability described constitutes a path traversal flaw resulting from insufficient validation of user-supplied input within the affected operating systems. In software architecture, path traversal attacks exploit inadequate sanitization mechanisms that allow an attacker to manipulate file paths by injecting special characters or sequences such as dot-dot-slash (../) or their URL-encoded equivalents. When an application fails to strictly validate these inputs against a predefined whitelist of allowed directories and files, it may inadvertently resolve the maliciously crafted path to locations outside the intended scope. This specific instance indicates that the underlying logic did not properly restrict file system access boundaries, thereby creating a vector through which external entities could influence internal resource location resolution mechanisms.
The operational impact of this flaw is significant as it grants an application the ability to modify protected system files. In modern mobile operating systems like iOS and iPadOS, strict sandboxing principles are enforced to isolate applications from one another and from critical system components. However, when path traversal vulnerabilities exist within privileged processes or improperly configured app interfaces, these isolation boundaries can be bypassed. An attacker who successfully exploits this condition could overwrite configuration files, inject malicious code into system binaries, or alter security policies that govern device behavior. Such modifications compromise the integrity of the operating environment and may lead to privilege escalation, where a lower-privileged process gains higher-level permissions, effectively undermining the core security model designed to protect user data and system stability.
This type of vulnerability aligns with Common Weakness Enumeration identifier CWE-22: Improper Limitation of a Pathname to a Restricted Directory. The failure lies in the application's inability to enforce strict directory confinement, allowing access to resources beyond the designated safe zone. From an offensive security perspective, this exploitation technique is often categorized under MITRE ATT&CK techniques related to Defense Evasion and Privilege Escalation, specifically those involving file system manipulation or persistence through modification of critical system artifacts. The ability to write to protected areas suggests a breakdown in access control lists or mandatory access controls that should normally prevent such operations unless explicitly authorized by the kernel or security framework.
Mitigation strategies for this vulnerability primarily involve rigorous input validation and defense-in-depth architectural practices. Developers must implement strict allow-listing of permitted file paths rather than relying on block-lists which are prone to bypass via encoding variations or symbolic links. Additionally, employing chroot jails or sandboxed environments with minimal permissions can limit the blast radius even if a traversal attempt succeeds. On the system level, ensuring that critical directories have immutable attributes and restricting write access to only trusted processes helps prevent unauthorized modifications. The release of iOS 26.7, iPadOS 26.7, iOS 27, iPadOS 27, and watchOS 27 addresses these issues by patching the underlying validation logic, thereby restoring proper boundary enforcement between application data and protected system resources. Users are advised to update their devices immediately to eliminate this attack surface and maintain the integrity of their mobile environments against potential exploitation attempts.