CVE-2025-43210: 
macOS vulnerability analysis and mitigation

CVE-2025-43210 is an out-of-bounds access vulnerability in Apple's CoreMedia framework that can be triggered by processing a maliciously crafted media file, potentially leading to unexpected app termination or process memory corruption. It was discovered by Hossein Lotfi (@hosselot) of Trend Micro Zero Day Initiative and disclosed by Apple on July 29, 2025. The vulnerability affects iOS and iPadOS (before 18.6 and 17.7.9), macOS Sequoia (before 15.6), macOS Sonoma (before 14.7.7), macOS Ventura (before 13.7.7), tvOS (before 18.6), visionOS (before 2.6), and watchOS (before 11.6). It carries a CVSS v3.1 base score of 6.3 (Medium) (Apple iOS 18.6 Advisory, Apple macOS Sequoia Advisory).

The vulnerability is classified under CWE-125 (Out-of-bounds Read) and CWE-787 (Out-of-bounds Write), residing in Apple's CoreMedia framework — the system component responsible for media file processing across Apple platforms. The root cause is insufficient bounds checking when parsing media file data structures, which can result in reads or writes beyond allocated memory buffers. Exploitation requires user interaction: a victim must open or process a specially crafted media file (e.g., via a downloaded file, email attachment, or malicious app), making the attack vector network-based but requiring user interaction (CAPEC-540: Overread Buffers). Apple addressed the issue with improved bounds checking in the patched releases (Apple iOS 18.6 Advisory, Apple macOS Sequoia Advisory).

Successful exploitation can cause unexpected application termination (denial of service) or corrupt process memory, which may be leveraged to achieve arbitrary code execution in the context of the affected application. The vulnerability affects confidentiality, integrity, and availability at a low-to-moderate level, with potential for memory disclosure or code execution depending on how the out-of-bounds access is triggered. Given CoreMedia's broad use across iOS, macOS, tvOS, visionOS, and watchOS, the attack surface spans a wide range of Apple devices and media-processing applications (Apple iOS 18.6 Advisory, Apple macOS Sequoia Advisory).

1. Craft a malicious media file: Create a specially crafted media file (e.g., a video or audio file) that contains malformed data structures designed to trigger out-of-bounds memory access in Apple's CoreMedia framework during parsing.
2. Deliver the file to the target: Distribute the malicious file via email attachment, messaging app, malicious website, or a rogue application that prompts the user to open the file on a vulnerable Apple device.
3. Trigger media processing: Induce the victim to open or preview the file using any application that invokes CoreMedia for media parsing (e.g., QuickTime Player, Photos, Safari, Mail).
4. Exploit memory corruption: The malformed file triggers an out-of-bounds read or write in CoreMedia, corrupting process memory. Depending on the specific memory layout, this may cause an application crash or, with additional exploitation primitives, enable arbitrary code execution in the context of the processing application.
5. Achieve objective: If code execution is achieved, the attacker can access user data, install persistent malware, or pivot to further system compromise within the app's sandbox (Apple iOS 18.6 Advisory, Apple macOS Sequoia Advisory).

• Logs: Repeated or unexpected application crashes (crash logs referencing CoreMedia framework, e.g., com.apple.CoreMedia) when opening media files; crash reports in /Library/Logs/DiagnosticReports/ or ~/Library/Logs/DiagnosticReports/ with stack traces involving CoreMedia.
• File System: Presence of unexpected or suspicious media files (e.g., .mov, .mp4, .m4v, .m4a) in Downloads, Temp, or application data directories from unknown sources.
• Process: Unusual child processes spawned by media-processing applications (e.g., QuickTime Player, Photos) immediately after opening a media file; unexpected network connections from media apps following file processing.
• Network: Outbound connections from media-processing applications to unknown external IP addresses shortly after a media file is opened, which may indicate post-exploitation activity.

Apple has released patches addressing CVE-2025-43210 in the following updates released on July 29, 2025: iOS 18.6 and iPadOS 18.6, iPadOS 17.7.9, macOS Sequoia 15.6, macOS Sonoma 14.7.7, macOS Ventura 13.7.7, tvOS 18.6, visionOS 2.6, and watchOS 11.6. Users should update all affected Apple devices to these versions or later immediately via System Settings > General > Software Update (macOS) or Settings > General > Software Update (iOS/iPadOS/watchOS/tvOS). As a temporary workaround prior to patching, users should avoid opening media files from untrusted or unknown sources (Apple iOS 18.6 Advisory, Apple macOS Sequoia Advisory, Apple macOS Sonoma Advisory).

The vulnerability was reported by Hossein Lotfi (@hosselot) of Trend Micro Zero Day Initiative, who has a track record of discovering media-parsing vulnerabilities in Apple products. The Zero Day Initiative published an advisory (ZDI-25-681) referencing this issue. Coverage appeared on 9to5Mac and ISC SANS shortly after Apple's disclosure, noting the breadth of the July 2025 security update which addressed approximately 95 vulnerabilities across Apple's product line. The CIS also issued an advisory noting multiple vulnerabilities in Apple products could allow for arbitrary code execution (ZDI Advisory, 9to5Mac, CIS Advisory).