CVE-2026-20675: 
macOS vulnerability analysis and mitigation

CVE-2026-20675 is an out-of-bounds read vulnerability in Apple's ImageIO framework that allows disclosure of user information when processing a maliciously crafted image file. It was disclosed and patched on February 11, 2026, affecting iOS prior to 18.7.5, iOS/iPadOS prior to 26.3, macOS Sonoma prior to 14.8.4, macOS Sequoia prior to 15.7.4, macOS Tahoe prior to 26.3, tvOS prior to 26.3, visionOS prior to 26.3, and watchOS prior to 26.3. The vulnerability was discovered by George Karchemsky (@gkarchemsky) working with Trend Micro Zero Day Initiative and carries a CVSS v3.1 base score of 5.5 (Medium) (Apple Advisory, Apple iOS 18.7.5).

The root cause is an out-of-bounds read (CWE-125) in Apple's ImageIO image processing library, resulting from insufficient bounds checking when parsing maliciously crafted image files. The attack vector is local (AV:L) and requires user interaction — specifically, a user must open or process a specially crafted image — but requires no privileges. The Zero Day Initiative published an advisory (ZDI-26-174) characterizing the vulnerability as an integer overflow in ImageIO's SGI file parsing that enables out-of-bounds memory reads, potentially exposing sensitive in-memory data (ZDI Advisory, Apple Advisory).

Successful exploitation leads to disclosure of sensitive user information stored in process memory, with a high confidentiality impact and no effect on integrity or availability. An attacker could craft a malicious image file and deliver it to a target user; upon processing (e.g., via the Photos app, Messages preview, or any application using ImageIO), memory contents such as credentials, authentication tokens, or personal data could be leaked. The attack is constrained to local execution with required user interaction, limiting its scope, but the breadth of affected Apple platforms — iOS, iPadOS, macOS, tvOS, watchOS, and visionOS — makes the potential exposure significant (Apple Advisory, ZDI Advisory).

1. Craft a malicious image: Create a specially crafted SGI (or other ImageIO-supported) image file that triggers an integer overflow during parsing, causing an out-of-bounds read in Apple's ImageIO framework.
2. Deliver the image to the target: Distribute the malicious image via email attachment, iMessage, a web page, AirDrop, or any other vector that causes the target device to process the image (e.g., thumbnail generation, preview rendering).
3. Trigger image processing: The victim opens or previews the image on an unpatched Apple device, causing the vulnerable ImageIO code path to execute.
4. Capture leaked memory: The out-of-bounds read exposes adjacent memory contents — potentially including sensitive user data such as credentials or tokens — which may be accessible to the attacker depending on the delivery mechanism and application context (ZDI Advisory, Apple Advisory).

• File System: Presence of unexpected or suspicious image files (particularly SGI format, .sgi, .rgb, .rgba, .bw) in user download directories, temporary folders, or messaging app caches.
• Logs: Application crash logs or diagnostic reports referencing ImageIO framework exceptions or memory access violations when processing image files; entries in ~/Library/Logs/DiagnosticReports/ related to ImageIO.
• Process: Unusual memory access patterns or crashes in processes that invoke ImageIO (e.g., imagent, Photos, MobileSMS, Safari) on unpatched Apple devices.
• Network: Unexpected outbound connections from image-processing applications shortly after opening an image from an untrusted source, which could indicate a chained exploit scenario.

Apple has released patches addressing this vulnerability across all affected platforms. Users should update to: iOS 18.7.5 or later, iOS 26.3 or later, iPadOS 18.7.5 or later, iPadOS 26.3 or later, macOS Sonoma 14.8.4 or later, macOS Sequoia 15.7.4 or later, macOS Tahoe 26.3 or later, tvOS 26.3 or later, watchOS 26.3 or later, and visionOS 26.3 or later. No configuration-based workaround is available; upgrading to a patched version is the only remediation. As an interim measure, users should avoid opening image files from untrusted or unknown sources (Apple iOS 18.7.5, Apple macOS Sequoia, Apple watchOS).

The vulnerability was reported by George Karchemsky (@gkarchemsky) through the Trend Micro Zero Day Initiative, which published advisory ZDI-26-174 on March 10, 2026, providing additional technical characterization of the flaw as an integer overflow in SGI file parsing within ImageIO (ZDI Advisory). Coverage appeared across security aggregators including SANS ISC, Tenable, and VulDB shortly after Apple's February 11, 2026 disclosure. The vulnerability was part of a broader Apple security update addressing over 90 vulnerabilities across Apple platforms, which received general media attention (SANS ISC).