CVE-2021-30860
📋 TL;DR
This vulnerability allows arbitrary code execution when processing malicious PDF files due to an integer overflow in Apple's PDF processing components. It affects multiple Apple operating systems and has been actively exploited in the wild. Users who open untrusted PDF files on vulnerable systems are at risk.
💻 Affected Systems
- iOS
- iPadOS
- macOS
- watchOS
📦 What is this software?
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 →Poppler by Freedesktop
Watchos by Apple
Xpdf by Xpdfreader
⚠️ Risk & Real-World Impact
Worst Case
Complete system compromise with attacker gaining full control of the device, allowing data theft, persistence installation, and lateral movement.
Likely Case
Malicious PDFs delivered via phishing or compromised websites execute arbitrary code, leading to data exfiltration, ransomware deployment, or credential theft.
If Mitigated
With proper patching and security controls, impact is limited to isolated incidents with minimal data exposure.
🎯 Exploit Status
Apple confirmed active exploitation. Exploit requires user interaction to open malicious PDF but no authentication. Multiple public disclosures contain technical details.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Security Update 2021-005 Catalina, iOS 14.8, iPadOS 14.8, macOS Big Sur 11.6, watchOS 7.6.2
Vendor Advisory: https://support.apple.com/en-us/HT212804
Restart Required: Yes
Instructions:
1. Open System Preferences > Software Update on macOS. 2. Open Settings > General > Software Update on iOS/iPadOS. 3. Open Watch app > General > Software Update on watchOS. 4. Install all available updates. 5. Restart device when prompted.
🔧 Temporary Workarounds
Disable PDF Preview
allPrevent automatic PDF rendering in browsers and email clients
Browser-specific: Disable PDF preview in Chrome/Firefox/Safari settings
Email clients: Disable automatic image/attachment loading
Application Sandboxing
macOSUse sandboxed PDF viewers that limit system access
Use third-party PDF viewers with sandboxing enabled
Configure macOS Gatekeeper to restrict unsigned applications
🧯 If You Can't Patch
- Block PDF files at network perimeter using content filtering
- Implement application allowlisting to prevent unauthorized PDF viewers
🔍 How to Verify
Check if Vulnerable:
Check OS version: macOS: About This Mac > Overview; iOS/iPadOS: Settings > General > About; watchOS: Watch app > General > AboutCheck Version:
macOS: sw_vers -productVersion; iOS/iPadOS: Settings > General > About > Version; watchOS: Watch app > General > About > VersionVerify Fix Applied:
Verify installed version matches or exceeds patched versions listed in fix_official.patch_version📡 Detection & Monitoring
Log Indicators:
- Unexpected PDF processing crashes in system logs
- Suspicious PDF file access from untrusted sources
- Unusual process spawning from PDF-related applications
Network Indicators:
- PDF downloads from suspicious domains
- Unusual outbound connections after PDF file access
SIEM Query:
source="*system.log*" AND "PDF" AND ("crash" OR "exception") OR process_name="Preview" AND parent_process NOT IN ("Finder", "Mail")🔗 References
- http://seclists.org/fulldisclosure/2021/Sep/25
- http://seclists.org/fulldisclosure/2021/Sep/26
- http://seclists.org/fulldisclosure/2021/Sep/27
- http://seclists.org/fulldisclosure/2021/Sep/28
- http://seclists.org/fulldisclosure/2021/Sep/38
- http://seclists.org/fulldisclosure/2021/Sep/39
- http://seclists.org/fulldisclosure/2021/Sep/40
- http://seclists.org/fulldisclosure/2021/Sep/50
- http://www.openwall.com/lists/oss-security/2022/09/02/11
- https://security.gentoo.org/glsa/202209-21
- https://support.apple.com/en-us/HT212804
- https://support.apple.com/en-us/HT212805
- https://support.apple.com/en-us/HT212806
- https://support.apple.com/en-us/HT212807
- https://support.apple.com/kb/HT212824
- http://seclists.org/fulldisclosure/2021/Sep/25
- http://seclists.org/fulldisclosure/2021/Sep/26
- http://seclists.org/fulldisclosure/2021/Sep/27
- http://seclists.org/fulldisclosure/2021/Sep/28
- http://seclists.org/fulldisclosure/2021/Sep/38
- http://seclists.org/fulldisclosure/2021/Sep/39
- http://seclists.org/fulldisclosure/2021/Sep/40
- http://seclists.org/fulldisclosure/2021/Sep/50
- http://www.openwall.com/lists/oss-security/2022/09/02/11
- https://security.gentoo.org/glsa/202209-21
- https://support.apple.com/en-us/HT212804
- https://support.apple.com/en-us/HT212805
- https://support.apple.com/en-us/HT212806
- https://support.apple.com/en-us/HT212807
- https://support.apple.com/kb/HT212824
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-30860
