CVE-2026-84524 in iOS
Summary
by MITRE • 09/15/2026
An out-of-bounds read was addressed with improved bounds checking. This issue is fixed in iOS 26.7 and iPadOS 26.7, iOS 27 and iPadOS 27, macOS Golden Gate 27, macOS Sequoia 15.8, macOS Tahoe 26.7, tvOS 27, visionOS 27, watchOS 27. Processing a maliciously crafted font file may lead to unexpected app termination.
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Analysis
by VulDB Data Team • 09/15/2026
The vulnerability described involves an out-of-bounds read condition within the system's font processing subsystem, specifically triggered by malformed or maliciously constructed font files. This type of flaw typically arises when software fails to properly validate input data before accessing memory locations associated with that data. In this instance, the application responsible for parsing font structures did not adequately verify whether the requested byte offsets fell within the allocated buffer boundaries. When a crafted file contains pointers or length fields that exceed the actual size of the embedded resource, the parser attempts to read from memory addresses outside its permitted scope. This behavior is classified under CWE-125, which defines out-of-bounds read vulnerabilities where software reads data past the end or before the beginning of the intended buffer. Such errors can lead to information disclosure if sensitive data residing in adjacent memory regions is exposed, although in this specific context, the primary observed consequence was application instability rather than direct data leakage.
The operational impact of exploiting this flaw centers on denial of service through unexpected process termination. When a user or automated system processes a maliciously crafted font file using affected applications, the out-of-bounds read triggers an exception within the operating environment. Depending on the specific implementation details and security mitigations in place at runtime, such as address space layout randomization or stack canaries, this may result in immediate crash of the application handling the font data. While modern mobile and desktop operating systems often isolate processes to limit lateral movement, a successful exploit could still disrupt user workflows by causing critical system components or third-party applications that rely on font rendering services to terminate unexpectedly. This degradation of service affects availability, which is one of the three core pillars of information security alongside confidentiality and integrity. The vulnerability does not appear to grant arbitrary code execution based on the provided description, but rather results in a crash state, limiting its severity from critical to moderate or high depending on the attack vector's accessibility.
Mitigation strategies primarily involve applying the software updates released by Apple for iOS 26.7, iPadOS 26.7, macOS Sequoia 15.8 and later versions including Golden Gate 27 and Tahoe 26.7, as well as tvOS 27, visionOS 27, and watchOS 27. These updates contain improved bounds checking logic that ensures all memory accesses are validated against the actual size of the input buffer before execution proceeds. For organizations managing large fleets of devices, ensuring timely patch deployment is essential to close this attack surface. Additionally, users should exercise caution when opening font files from untrusted sources, as social engineering tactics may be used to deliver malicious payloads disguised as legitimate typography assets. From a defensive posture perspective, implementing strict input validation at the application level and utilizing sandboxing mechanisms can further reduce the risk of exploitation. The ATT&CK framework categorizes this type of vulnerability under techniques related to initial access or execution if it leads to code execution, but in its current manifestation as a crash-inducing flaw, it aligns more closely with resource exhaustion or denial-of-service vectors within the impact phase. Continuous monitoring for anomalous process terminations and maintaining up-to-date security patches remain the most effective defenses against such memory safety issues.