CVE-2026-84510: Apple iPadOS Heap Buffer Overflow Vulnerability

CVE-2026-84510 Overview

CVE-2026-84510 is a heap buffer overflow [CWE-122] affecting Apple iOS, iPadOS, and macOS. The flaw resides in the volume mounting subsystem. Mounting a maliciously crafted volume triggers an out-of-bounds write on the heap, leading to unexpected system termination. Apple resolved the issue with improved bounds checking.

The vulnerability requires user interaction to mount the attacker-controlled volume. Successful exploitation impacts availability, causing denial of service through kernel or system process crashes. Apple addressed the flaw in iOS 26.7, iPadOS 26.7, iOS 27, iPadOS 27, macOS Golden Gate 27, macOS Sequoia 15.8, and macOS Tahoe 26.7.

Critical Impact
An attacker who convinces a user to mount a crafted disk image or external volume can trigger unexpected system termination on iOS, iPadOS, and macOS devices.

Affected Products

Apple iOS (fixed in iOS 26.7 and iOS 27)
Apple iPadOS (fixed in iPadOS 26.7 and iPadOS 27)
Apple macOS (fixed in macOS Sequoia 15.8, macOS Tahoe 26.7, and macOS Golden Gate 27)

Discovery Timeline

2026-09-14 - CVE-2026-84510 published to the National Vulnerability Database
2026-09-18 - Last updated in NVD database

Technical Details for CVE-2026-84510

Vulnerability Analysis

The vulnerability is a heap-based buffer overflow within Apple's volume mounting logic. When the operating system parses metadata from a mounted volume, insufficient bounds checking allows attacker-controlled data to overflow a heap allocation. The result is corruption of adjacent heap memory and unexpected system termination.

Exploitation requires that a user mount an attacker-supplied volume such as a disk image or removable storage device. The vulnerability affects Apple's mobile and desktop operating systems that share filesystem handling code. Apple's advisory attributes the fix to improved bounds checking during volume parsing.

Root Cause

The root cause is missing or incorrect validation of length fields within volume metadata before those values are used to size or index heap buffers. This class of defect, tracked as [CWE-122], occurs when parsers trust attacker-controlled sizes without enforcing upper bounds against the destination allocation.

Attack Vector

The attack vector requires user interaction to attach and mount a crafted volume. Delivery methods include emailed disk image attachments, downloaded .dmg files, or physical media presented to a target device. Refer to the Apple advisories for platform-specific fix details: Apple Support Article #149034, Apple Support Article #149035, Apple Support Article #149041, Apple Support Article #149042, and Apple Support Article #149043.

Detection Methods for CVE-2026-84510

Indicators of Compromise

Repeated unexpected system reboots or kernel panics on iOS, iPadOS, or macOS endpoints following mount events
Presence of untrusted .dmg, .iso, or filesystem image files delivered by email, download, or removable media
Diagnostic reports referencing crashes in diskimages-helper, mount_*, or related filesystem daemons

Detection Strategies

Monitor macOS unified logs and iOS crash reports for repeated terminations tied to mount or filesystem subsystems
Correlate download or transfer of disk image files with subsequent mount events on the same device
Track deployment coverage of iOS 26.7, iPadOS 26.7, macOS Sequoia 15.8, macOS Tahoe 26.7, and later builds

Monitoring Recommendations

Alert on unusual mount activity from removable storage or downloaded disk images on managed Apple devices
Review MDM compliance dashboards for endpoints still running vulnerable OS builds
Retain crash and diagnostic telemetry to support post-incident analysis of suspected exploitation attempts

How to Mitigate CVE-2026-84510

Immediate Actions Required

Update all Apple endpoints to iOS 26.7, iPadOS 26.7, iOS 27, iPadOS 27, macOS Sequoia 15.8, macOS Tahoe 26.7, or macOS Golden Gate 27
Instruct users to avoid mounting disk images or external volumes from untrusted sources
Prioritize patching of shared or high-value macOS systems that regularly handle external media

Patch Information

Apple released fixes across five advisories covering the affected platforms. Deploy the updates referenced in Apple Support Article #149034, Apple Support Article #149035, Apple Support Article #149041, Apple Support Article #149042, and Apple Support Article #149043 using an MDM solution or the built-in Software Update mechanism.

Workarounds

Restrict mounting of external volumes and disk images via configuration profiles or MDM policy where feasible
Block delivery of disk image file types at the email gateway when business use cases do not require them
Educate users to verify the origin of any .dmg or filesystem image before mounting

bash

# Verify current macOS build against the patched versions
sw_vers -productVersion

# Trigger a software update check on macOS
sudo softwareupdate --list
sudo softwareupdate --install --all --restart