Login Sign Up

CVE-2021-1838

7.8 HIGH
Remote Code Execution

📋 TL;DR

This vulnerability allows arbitrary code execution by processing a maliciously crafted image on iOS and iPadOS devices. Attackers could exploit this to take control of affected devices. All users running vulnerable iOS/iPadOS versions are affected.

💻 Affected Systems

Products:
  • iPhone
  • iPad
Versions: iOS/iPadOS versions before 14.4
Operating Systems: iOS, iPadOS
Default Config Vulnerable: ⚠️ Yes
Notes: All default configurations are vulnerable. No special settings required for exploitation.

📦 What is this software?

Ipados by Apple

View all CVEs affecting Ipados →

Iphone Os by Apple

View all CVEs affecting Iphone Os →

⚠️ Risk & Real-World Impact

🔴

Worst Case

Complete device compromise allowing data theft, surveillance, ransomware deployment, or use as botnet node

🟠

Likely Case

Targeted attacks against specific individuals to steal sensitive data or credentials

🟢

If Mitigated

No impact if patched; limited impact if device has strict app restrictions and network segmentation

🌐 Internet-Facing: MEDIUM - Requires user interaction (opening malicious image) but can be delivered via web/messaging
🏢 Internal Only: LOW - Requires local access or internal phishing to deliver malicious image

🎯 Exploit Status

Public PoC: ✅ No
Weaponized: UNKNOWN
Unauthenticated Exploit: ✅ No
Complexity: MEDIUM

Requires user to process malicious image (open/view). No authentication bypass needed beyond user interaction.

🛠️ Fix & Mitigation

✅ Official Fix

Patch Version: iOS 14.4, iPadOS 14.4

Vendor Advisory: https://support.apple.com/en-us/HT212146

Restart Required: Yes

Instructions:

1. Open Settings app. 2. Tap General. 3. Tap Software Update. 4. Download and install iOS 14.4 or later. 5. Restart device when prompted.

🔧 Temporary Workarounds

Disable automatic image processing

ios

Prevent automatic loading/processing of images in messages and emails

Settings > Messages > toggle off 'Load Remote Images'
Settings > Mail > toggle off 'Load Remote Images'

🧯 If You Can't Patch

  • Restrict image sources to trusted senders only
  • Use web-based email clients that process images server-side

🔍 How to Verify

Check if Vulnerable:

Check iOS version: Settings > General > About > Version. If version is below 14.4, device is vulnerable.

Check Version:

Settings > General > About > Version

Verify Fix Applied:

Verify iOS version is 14.4 or higher in Settings > General > About > Version

📡 Detection & Monitoring

Log Indicators:

  • Unusual process crashes related to image processing
  • Suspicious file access patterns from image-related processes

Network Indicators:

  • Downloads of suspicious image files from untrusted sources
  • Unusual outbound connections after image processing

SIEM Query:

process:image* AND (crash OR memory_violation) OR file_type:image AND source_ip:external

📊 Metadata

CVE ID: CVE-2021-1838
CVSS v3 Score: 7.8 (HIGH)
CVSS Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
Published: September 8, 2021
Last Updated: November 21, 2024

🔗 References

📤 Share & Export

📄 Export Markdown 📋 Export JSON