CVE-2026-20611: Apple OS Buffer Overflow Vulnerability

CVE-2026-20611 Overview

CVE-2026-20611 is an out-of-bounds read vulnerability (CWE-125) affecting multiple Apple operating systems including macOS, iOS, iPadOS, watchOS, tvOS, and visionOS. The vulnerability exists in media file processing functionality where insufficient bounds checking allows an attacker to craft a malicious media file that, when processed, can read memory beyond the intended buffer boundaries.

Critical Impact

Processing a maliciously crafted media file may lead to unexpected application termination or corrupt process memory, potentially exposing sensitive information stored in adjacent memory regions.

Affected Products

• watchOS 26.3 and earlier
• tvOS 26.3 and earlier
• macOS Tahoe 26.3 and earlier
• macOS Sonoma 14.8.4 and earlier
• macOS Sequoia 15.7.4 and earlier
• iOS 18.7.5 and iPadOS 18.7.5 and earlier
• visionOS 26.3 and earlier
• iOS 26.3 and iPadOS 26.3 and earlier

Discovery Timeline

• February 11, 2026 - CVE-2026-20611 published to NVD
• February 12, 2026 - Last updated in NVD database

Technical Details for CVE-2026-20611

Vulnerability Analysis

This vulnerability stems from improper bounds checking within Apple's media processing components. When a user opens or previews a specially crafted media file, the parsing routine fails to properly validate the size of data structures embedded within the file format. This allows an attacker to specify offset or length values that cause the application to read beyond the allocated buffer.

The out-of-bounds read can result in two primary outcomes: application crashes due to accessing invalid memory addresses, or information disclosure if the out-of-bounds memory contains sensitive data that gets processed and potentially exposed. Since the attack requires local access and user interaction (opening a malicious file), exploitation typically occurs through social engineering vectors such as phishing emails with malicious media attachments.

Root Cause

The root cause is classified as CWE-125 (Out-of-Bounds Read), indicating that the software reads data past the end or before the beginning of the intended buffer. In this case, the media file parsing code did not adequately validate boundary conditions when processing variable-length fields or arrays within media container formats. Apple addressed this by implementing improved bounds checking to ensure all memory accesses remain within allocated buffer regions.

Attack Vector

The attack requires local access to the target system with user interaction. An attacker must craft a malicious media file and convince the victim to open or process it. Attack scenarios include:

• Sending malicious media files via email attachments
• Hosting malicious media on websites that victims visit
• Distributing through messaging applications or file sharing services
• Embedding malicious media in documents that trigger automatic preview

When the victim's device processes the crafted media file, the out-of-bounds read occurs during parsing, potentially leading to application termination or memory corruption. The vulnerability does not require elevated privileges, as it exploits the normal media processing pipeline available to standard users.

Detection Methods for CVE-2026-20611

Indicators of Compromise

• Unexpected crashes in media-related system processes such as mediaserverd, avconvertd, or similar daemons
• Crash reports indicating out-of-bounds access or memory corruption in media frameworks
• Presence of unusually structured media files with abnormal header values or metadata sizes
• Application terminations when opening media files from untrusted sources

Detection Strategies

• Monitor system crash logs for patterns indicating memory access violations in media processing components
• Implement endpoint detection rules for anomalous media file structures with suspicious size parameters
• Deploy behavioral analysis to detect unusual process crashes following media file operations
• Enable crash reporting and analytics to identify patterns consistent with exploitation attempts

Monitoring Recommendations

• Configure logging for media framework activities on enterprise-managed Apple devices
• Implement file integrity monitoring on systems handling untrusted media content
• Establish baseline crash rates to identify anomalous spikes that may indicate attack campaigns
• Monitor for suspicious media file downloads or email attachments in network traffic

How to Mitigate CVE-2026-20611

Immediate Actions Required

• Update all affected Apple devices to the patched versions immediately
• Advise users to avoid opening media files from untrusted or unknown sources until patches are applied
• Review recent crash logs on critical systems for indicators of potential exploitation
• Implement email filtering to quarantine suspicious media file attachments

Patch Information

Apple has released security updates addressing this vulnerability across all affected platforms. Organizations should deploy the following patched versions:

For detailed patch information, refer to Apple's security advisories:

• Apple Security Advisory #126346
• Apple Security Advisory #126347
• Apple Security Advisory #126348
• Apple Security Advisory #126349
• Apple Security Advisory #126350
• Apple Security Advisory #126351
• Apple Security Advisory #126352
• Apple Security Advisory #126353

Workarounds

• Configure email clients to block or quarantine media file attachments from external senders
• Disable automatic media preview features where possible to prevent passive exploitation
• Implement application sandboxing policies to limit the impact of potential memory disclosure
• Use Mobile Device Management (MDM) to restrict media file handling on enterprise devices until patches are deployed