CVE-2026-84593 in iOS
Summary
by MITRE • 09/15/2026
A use after free issue was addressed with improved memory management. This issue is fixed in iOS 27 and iPadOS 27. An app may be able to cause unexpected system termination.
If you want to get the best quality for vulnerability data then you always have to consider VulDB.
Analysis
by VulDB Data Team • 09/15/2026
The vulnerability described constitutes a classic Use-After-Free (UAF) flaw, categorized under CWE-416 within the Common Weakness Enumeration framework. This type of memory corruption error occurs when software continues to use a pointer after it has been freed or deallocated by the system. In the context of iOS and iPadOS versions prior to 27, this specific instance stems from inadequate memory management practices where an application can trigger operations on memory regions that have already been released back to the operating system's pool. The root cause lies in a failure to properly invalidate pointers or update reference counts after deallocation, leaving dangling references that point to potentially reused or invalid memory addresses.
From a technical perspective, when an app causes this condition, it attempts to access memory that is no longer reserved for its use. Depending on the timing and state of the system's memory allocator, this freed memory might have been reallocated to another process or data structure, leading to unpredictable behavior. Alternatively, if the memory remains unmapped or marked as invalid by the operating system's security mechanisms such as Kernel Address Space Layout Randomization (KASLR) or Data Execution Prevention (DEP), the access attempt will result in a segmentation fault or similar critical error. This mechanism is exploited when an attacker-controlled application can precisely time its operations to trigger the use of these dangling pointers, effectively bypassing standard memory safety checks that are otherwise enforced by modern mobile operating systems.
The operational impact of this vulnerability is primarily characterized by system instability and denial of service conditions. As noted in the advisory, the immediate consequence is unexpected system termination. This means that a malicious or poorly coded application can crash critical system services or the entire device interface without requiring elevated privileges to execute arbitrary code directly. While UAF vulnerabilities are often associated with privilege escalation due to their potential for memory corruption and control flow hijacking, this specific report highlights reliability issues rather than direct remote code execution capabilities. However, in a broader security context, such instability can be leveraged as part of a larger attack chain where the crash is used to bypass certain sandbox restrictions or trigger secondary vulnerabilities that lead to higher-level compromise.
This vulnerability aligns with several tactics within the MITRE ATT&CK framework for mobile platforms. It relates to Defense Evasion techniques where an attacker might use crashes to disrupt security monitoring or forensic analysis, as well as Impact categories involving Denial of Service against system availability. The lack of robust memory management in earlier versions allowed applications to interact with kernel-level resources in unsafe ways, violating the principle of least privilege and isolation that mobile operating systems strive to maintain between user-space applications and core system components.
Mitigation for this issue is addressed through improved memory management protocols implemented in iOS 27 and iPadOS 27. These updates likely include stricter enforcement of pointer validity checks, enhanced runtime detection of dangling references, and potentially the introduction or strengthening of automated static analysis tools during development to catch such errors before deployment. For users currently on affected versions, it is imperative to update the operating system immediately to patch this memory safety flaw. Developers should also audit their codebases for similar patterns, ensuring that pointers are nullified after free operations and that lifecycle management accurately tracks object validity across asynchronous or concurrent execution paths.