CVE-2026-84596: Apple iPadOS Information Disclosure Flaw

CVE-2026-84596 Overview

CVE-2026-84596 is an out-of-bounds read vulnerability [CWE-125] affecting Apple's font processing components across the company's operating system portfolio. Processing a maliciously crafted font can result in the disclosure of process memory. The issue impacts iOS, iPadOS, macOS, tvOS, visionOS, and watchOS. Apple addressed the flaw with improved bounds checking in iOS 27, iPadOS 27, macOS Golden Gate 27, tvOS 27, visionOS 27, and watchOS 27. Exploitation requires user interaction, typically opening or rendering an attacker-controlled font file. No public exploit or in-the-wild abuse has been reported at the time of publication.

Critical Impact
A remote attacker can leak sensitive process memory contents by delivering a crafted font, potentially exposing data useful for chaining further exploitation.

Affected Products

Apple iOS and iPadOS (fixed in version 27)
Apple macOS Golden Gate (fixed in version 27)
Apple tvOS, visionOS, and watchOS (fixed in version 27)

Discovery Timeline

2026-09-14 - CVE-2026-84596 published to the National Vulnerability Database
2026-09-16 - Last updated in NVD database

Technical Details for CVE-2026-84596

Vulnerability Analysis

The flaw resides in Apple's font parsing pipeline, which is shared across iOS, iPadOS, macOS, tvOS, visionOS, and watchOS. A crafted font file causes the parser to read beyond the bounds of an allocated buffer. This out-of-bounds read leaks adjacent process memory back into a context reachable by the attacker or the rendering application. Because font parsing is invoked implicitly by many system and third-party applications, the attack surface is broad. Leaked memory may contain pointers, cryptographic material, or other sensitive data that undermines address space layout randomization (ASLR) and enables follow-on exploitation.

Root Cause

The root cause is missing or insufficient bounds validation when processing structures inside a font file. Apple's advisory states the issue was resolved with improved bounds checking, which is characteristic of a classic out-of-bounds read [CWE-125]. Attacker-controlled length or offset fields drive the parser to access memory outside the intended buffer.

Attack Vector

The attack vector is network-adjacent and requires user interaction. An attacker delivers a malicious font through a webpage, document, message, or application that triggers font rendering. When the vulnerable parser processes the font, memory contents are disclosed to the attacker-controlled context. No privileges are required on the target device.

// No verified proof-of-concept is publicly available for CVE-2026-84596.
// Refer to Apple's security advisories for technical details.

Detection Methods for CVE-2026-84596

Indicators of Compromise

Unexpected font files delivered through email attachments, messaging apps, or downloaded documents from untrusted sources.
Application crashes or anomalous memory reads in processes that handle font rendering, such as browsers, document viewers, and messaging clients.
Outbound network activity from font-rendering processes following the opening of a document or webpage.

Detection Strategies

Inspect inbound files for malformed or non-standard font structures using content-aware email and web gateways.
Monitor endpoints for crashes and exception events in font-parsing libraries and correlate with recently opened content.
Baseline expected behavior of applications that consume fonts and alert on deviations such as unexpected memory access patterns.

Monitoring Recommendations

Ingest Apple endpoint telemetry, crash reports, and unified logs into a centralized analytics platform for retrospective hunting.
Track OS version inventory across the fleet to identify devices running versions prior to the fixed releases.
Alert on delivery of font file types (.ttf, .otf, .woff, .woff2) from external senders to high-value users.

How to Mitigate CVE-2026-84596

Immediate Actions Required

Update all Apple devices to iOS 27, iPadOS 27, macOS Golden Gate 27, tvOS 27, visionOS 27, and watchOS 27 or later.
Prioritize patching for high-risk users such as executives, developers, and administrators whose devices process untrusted content.
Verify mobile device management (MDM) policies enforce prompt installation of Apple security updates.

Patch Information

Apple has released fixes across all affected operating systems. Refer to the vendor advisories for release notes and installation guidance: Apple Support Article #149034, Apple Support Article #149035, Apple Support Article #149036, Apple Support Article #149037, and Apple Support Article #149038.

Workarounds

Avoid opening font files or documents from untrusted senders until patches are applied.
Restrict web browsing to trusted sites on unpatched devices, since fonts are commonly loaded from webpages.
Use email and web filtering to block or quarantine unexpected font file attachments at the perimeter.

bash

# Verify the installed macOS version and confirm the patch is applied
sw_vers -productVersion

# On iOS/iPadOS devices, confirm version via MDM query or Settings > General > About