CVE-2025-43400
📋 TL;DR
This CVE describes an out-of-bounds write vulnerability in font processing on Apple watchOS and tvOS. Attackers can exploit this by providing malicious fonts to cause app crashes or corrupt memory. Only users of affected Apple operating systems are impacted.
💻 Affected Systems
- Apple watchOS
- Apple tvOS
📦 What is this software?
Ipados by Apple
Ipados by Apple
Macos by Apple
macOS is Apple's desktop and laptop operating system powering Mac computers used by millions of professionals, developers, creative professionals, and enterprise users worldwide. Built on a Unix foundation with the Darwin kernel and modern Cocoa frameworks, macOS delivers a seamless ecosystem integr...
Learn more about Macos →Macos by Apple
macOS is Apple's desktop and laptop operating system powering Mac computers used by millions of professionals, developers, creative professionals, and enterprise users worldwide. Built on a Unix foundation with the Darwin kernel and modern Cocoa frameworks, macOS delivers a seamless ecosystem integr...
Learn more about Macos →Macos by Apple
macOS is Apple's desktop and laptop operating system powering Mac computers used by millions of professionals, developers, creative professionals, and enterprise users worldwide. Built on a Unix foundation with the Darwin kernel and modern Cocoa frameworks, macOS delivers a seamless ecosystem integr...
Learn more about Macos →⚠️ Risk & Real-World Impact
Worst Case
Arbitrary code execution leading to full device compromise if memory corruption can be weaponized into RCE
Likely Case
Application crashes (denial of service) and potential memory corruption leading to unstable system behavior
If Mitigated
Minimal impact with proper patching and security controls in place
🎯 Exploit Status
Requires processing malicious fonts, which typically requires user interaction or specific app functionality
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: watchOS 26.1, tvOS 26.1
Vendor Advisory: https://support.apple.com/en-us/125637
Restart Required: No
Instructions:
1. Go to Settings > General > Software Update on affected device. 2. Download and install watchOS 26.1 or tvOS 26.1. 3. Verify installation completes successfully.
🔧 Temporary Workarounds
Disable untrusted font sources
allPrevent installation or use of fonts from untrusted sources
🧯 If You Can't Patch
- Restrict font installation to trusted sources only
- Implement network segmentation to isolate vulnerable devices
🔍 How to Verify
Check if Vulnerable:
Check Settings > General > About > Version on Apple Watch or Apple TVCheck Version:
Settings > General > About > VersionVerify Fix Applied:
Confirm version is watchOS 26.1 or tvOS 26.1 or later📡 Detection & Monitoring
Log Indicators:
- Unexpected application crashes related to font processing
- Memory access violation logs
Network Indicators:
- Font downloads from untrusted sources
SIEM Query:
Application logs containing 'font', 'crash', or 'memory violation' on watchOS/tvOS devices