CVE-2026-84524: Apple iPadOS Buffer Overflow Vulnerability

CVE-2026-84524 Overview

CVE-2026-84524 is an out-of-bounds read vulnerability [CWE-125] affecting font file processing across Apple's operating system portfolio. Processing a maliciously crafted font file may trigger unexpected application termination. Apple addressed the flaw with improved bounds checking in iOS 26.7, iPadOS 26.7, iOS 27, iPadOS 27, macOS Golden Gate 27, macOS Sequoia 15.8, macOS Tahoe 26.7, tvOS 27, visionOS 27, and watchOS 27.

The vulnerability requires user interaction and originates from a network attack vector. Impact is limited to availability, resulting in denial of service rather than code execution or data disclosure.

Critical Impact
A crafted font file can be delivered through documents, web pages, or messaging applications to terminate the processing application, disrupting service on affected Apple devices.

Affected Products

Apple iOS and iPadOS (versions prior to 26.7 and 27)
Apple macOS Sequoia (prior to 15.8), macOS Tahoe (prior to 26.7), macOS Golden Gate (prior to 27)
Apple tvOS, visionOS, and watchOS (versions prior to 27)

Discovery Timeline

2026-09-14 - CVE-2026-84524 published to NVD
2026-09-18 - Last updated in NVD database

Technical Details for CVE-2026-84524

Vulnerability Analysis

The flaw resides in Apple's font parsing subsystem shared across iOS, iPadOS, macOS, tvOS, visionOS, and watchOS. When the font parser reads structured tables from a font file, it fails to validate offsets or lengths against the actual buffer size. A specifically constructed font causes the parser to read memory beyond the intended buffer boundary.

The result is an application crash rather than memory disclosure or code execution. Because font parsing runs inside many applications that render text, the crash surface is broad. Impact is confined to availability, which aligns with the vulnerability's Low availability rating.

Root Cause

The root cause is missing or insufficient bounds validation when parsing font table structures. The parser trusted offset and length fields inside the font container without verifying they fit within the mapped buffer. Apple's advisory describes the fix as "improved bounds checking," indicating that additional length and range checks now gate memory reads during font parsing.

Attack Vector

An attacker delivers a malicious font file to a target through any channel that triggers font rendering. Common delivery paths include embedded fonts in web pages, PDF or Office documents, email attachments, and messaging applications. The victim must open or preview content that invokes the vulnerable parser, satisfying the required user-interaction condition.

Successful exploitation terminates the application processing the font. No code execution, privilege escalation, or data exfiltration is achievable through this issue based on Apple's advisory and the CVSS metric set.

No public proof-of-concept, exploit database entry, or in-the-wild exploitation has been reported for CVE-2026-84524. The vulnerability is not listed in the CISA Known Exploited Vulnerabilities catalog.

Detection Methods for CVE-2026-84524

Indicators of Compromise

Repeated unexpected termination of applications that render text or open documents containing fonts.
Crash reports referencing font parsing frameworks such as CoreText, CoreGraphics, or the FontParser component.
Delivery of unusual font files (.ttf, .otf, .woff, .woff2) through email, chat, or web downloads immediately preceding crashes.

Detection Strategies

Collect application crash logs from managed Apple endpoints and alert on repeated crashes with font-parsing stack frames.
Inspect email and web gateway telemetry for font files delivered outside expected business workflows.
Correlate document or webpage rendering events with subsequent process termination on the same host.

Monitoring Recommendations

Track operating system version inventory to identify Apple endpoints still running vulnerable builds prior to iOS 26.7, iPadOS 26.7, macOS Sequoia 15.8, macOS Tahoe 26.7, tvOS 27, visionOS 27, and watchOS 27.
Monitor mobile device management (MDM) compliance reports for pending Apple security updates.
Alert on high-volume delivery of font attachments to end users, which may indicate scanning or targeted delivery.

How to Mitigate CVE-2026-84524

Immediate Actions Required

Deploy the Apple updates listed in the vendor advisories to all managed iPhone, iPad, Mac, Apple TV, Apple Vision Pro, and Apple Watch devices.
Prioritize devices that regularly process untrusted documents, email attachments, or third-party web content.
Verify update installation through MDM reporting after deployment.

Patch Information

Apple fixed CVE-2026-84524 in iOS 26.7, iPadOS 26.7, iOS 27, iPadOS 27, macOS Golden Gate 27, macOS Sequoia 15.8, macOS Tahoe 26.7, tvOS 27, visionOS 27, and watchOS 27. Full release notes and update instructions are available in the Apple advisories: Apple Support Document #149034, #149035, #149036, #149037, #149038, #149041, #149042, and #149043.

Workarounds

Restrict delivery of font file types (.ttf, .otf, .woff, .woff2) at email and web gateways where they are not required.
Disable automatic preview of attachments and rich content in messaging clients until patches are applied.
Advise users to avoid opening font files or documents from untrusted sources during the patch window.

bash

# Verify installed macOS build on managed endpoints
sw_vers -productVersion

# Trigger Apple software update check via command line
sudo softwareupdate --list
sudo softwareupdate --install --all --restart