CVE-2026-86874 in Xcode
Summary
by MITRE • 10/20/2026
An out-of-bounds read was addressed with improved input validation. This issue is fixed in Xcode 27. Parsing a maliciously crafted binary may lead to unexpected tool termination.
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Analysis
by VulDB Data Team • 10/20/2026
The vulnerability described constitutes an out-of-bounds read flaw within the parsing logic of Apple's Xcode development environment, specifically affecting version 27 and potentially earlier iterations depending on the specific build configuration. This type of memory safety error occurs when a program reads data from a memory location that lies outside the boundaries of the intended buffer or array structure. In the context of binary file analysis tools embedded within integrated development environments like Xcode, such vulnerabilities typically arise during the parsing phase where metadata headers, section tables, or symbol information are processed. The root cause is attributed to insufficient input validation mechanisms that fail to adequately verify the length and integrity of data structures before accessing them in memory. When a maliciously crafted binary file containing malformed headers or corrupted structural elements is submitted for analysis, the parser may calculate incorrect offsets or lengths, leading it to read from adjacent memory regions that do not contain valid executable code or expected metadata.
From an operational perspective, the primary impact of this vulnerability is the unexpected termination of the tool rather than arbitrary code execution, which distinguishes it as a denial-of-service vector in its immediate manifestation. While out-of-bounds reads are often associated with information disclosure if sensitive data resides in adjacent memory, the specific description indicates that the consequence is limited to application crash or forced closure. This behavior can disrupt development workflows by causing sudden loss of unsaved work or interrupting automated build and analysis pipelines. For security researchers and developers relying on Xcode for static analysis or debugging sessions involving third-party libraries or obfuscated binaries, this instability represents a significant reliability concern. The ability to trigger such crashes through specially crafted inputs means that an attacker could potentially cause service disruption in environments where these tools are used as part of continuous integration processes or when analyzing untrusted code samples provided by external parties.
The technical classification of this flaw aligns with Common Weakness Enumeration (CWE) standards, specifically mapping to CWE-125: Out-of-bounds Read. This weakness is characterized by the software reading data past the end, or before the beginning, of the intended buffer. It often leads to crashes, data corruption, or information leaks depending on what resides in the adjacent memory space and how the operating system handles such access violations. In terms of adversarial tactics, this vulnerability can be leveraged within the MITRE ATT&CK framework under techniques related to resource exhaustion or application crash exploitation, particularly if an attacker aims to destabilize a development environment as part of a broader supply chain attack strategy targeting software engineering tools. By causing the tool to terminate unexpectedly, attackers may attempt to bypass security checks that rely on continuous monitoring or logging during the analysis process.
Mitigation for this vulnerability relies primarily on the deployment of the official patch provided by Apple in Xcode version 27. Developers and organizations utilizing older versions must upgrade their development environments to ensure that improved input validation routines are active. These updates typically involve rigorous boundary checks before memory access operations, ensuring that all offsets calculated during binary parsing remain within valid limits defined by the file format specifications such as Mach-O or ELF standards. Additionally, defensive measures include implementing sandboxing for tools that process untrusted binaries and utilizing automated testing frameworks to validate input handling against fuzzed data sets. Security teams should also enforce strict policies regarding the analysis of third-party code samples, ensuring that any external binary inputs are processed in isolated environments where potential crashes do not compromise host system integrity or expose sensitive project artifacts. Regular updates to development tools remain critical for maintaining resilience against memory safety vulnerabilities inherent in complex parsing logic.