CVE-2026-65391 in iOS
Summary
by MITRE • 09/15/2026
An out-of-bounds write issue was addressed with improved bounds checking. This issue is fixed in Safari 26.6.1, iOS 26.6.1 and iPadOS 26.6.1, macOS Tahoe 26.6.2, tvOS 27, visionOS 27, watchOS 27. Processing maliciously crafted web content may lead to memory corruption.
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Analysis
by VulDB Data Team • 09/15/2026
The vulnerability described constitutes a critical out-of-bounds write flaw within the Safari rendering engine and associated WebKit components across multiple Apple operating systems including iOS, iPadOS, macOS Tahoe, tvOS, visionOS, and watchOS. This type of security defect arises when software writes data to a memory location that falls outside the boundaries of an intended buffer or array structure. In the context of web content processing, this typically occurs during the parsing or execution of complex JavaScript objects, HTML DOM manipulations, or binary data handling routines where input validation mechanisms fail to adequately verify index values against allocated memory limits. The root cause is identified as insufficient bounds checking within the internal logic that manages memory allocation and access for processed web elements.
From a technical perspective, an out-of-bounds write allows maliciously crafted content to overwrite adjacent memory locations with arbitrary data. This can corrupt heap metadata, alter function pointers, or modify critical application state variables stored in nearby memory regions. Unlike read-only vulnerabilities which primarily facilitate information disclosure, write operations provide the attacker with significant control over program execution flow. By carefully crafting the payload to target specific memory structures such as virtual method tables or exception handlers, an adversary can achieve arbitrary code execution within the context of the browser process. This represents a severe escalation from simple data leakage to full system compromise if sandboxing mechanisms are bypassed or fail due to the corruption.
The operational impact is substantial given that web browsers serve as primary gateways for internet access on these devices. Users processing maliciously crafted web content, such as specially designed HTML pages with embedded scripts or malformed media files, risk triggering this vulnerability automatically upon rendering. Successful exploitation could lead to remote code execution without user interaction beyond visiting the targeted URL. This compromises not only the confidentiality and integrity of data within the browser session but also potentially extends to other applications running on the device if privilege escalation techniques are employed following initial memory corruption. The widespread nature of Safari across Apple's ecosystem amplifies the potential blast radius, affecting personal devices used for banking, communication, and enterprise workloads.
Industry standards classify this flaw under CWE-787: Out-of-bounds Write, which highlights the failure to verify that a write operation remains within allocated memory boundaries. In terms of attack tactics, this vulnerability aligns with MITRE ATT&CK techniques related to Memory Corruption, specifically T1204.002 (User Execution: Malicious File) or potentially T1059 if it facilitates script execution leading further into lateral movement phases like Command and Scripting Interpreter usage. The exploitation chain often involves bypassing modern browser mitigations such as ASLR and DEP through heap grooming techniques that stabilize memory layout before triggering the write primitive.
Mitigation strategies primarily rely on applying the provided software updates which address these issues with improved bounds checking logic within WebKit. Administrators should ensure all devices are patched to Safari 26.6.1, iOS/iPadOS 26.6.1, macOS Tahoe 26.6.2, tvOS 27, visionOS 27, and watchOS 27 respectively. Beyond patching, defense-in-depth measures include enabling strict Content Security Policies to restrict inline script execution, utilizing browser sandboxing features effectively by keeping them enabled, and avoiding the opening of untrusted web content or downloaded files from unknown sources. Regular security awareness training for users regarding phishing attempts that deliver such malicious payloads remains a critical complementary control against exploitation in real-world scenarios.