CVE-2021-43086
📋 TL;DR
CVE-2021-43086 is a critical buffer overflow vulnerability in ARM's astcenc 3.2.0 ASTC texture compression encoder. When using the compression function with the -cl option, attackers can trigger a stack buffer overflow in the encode_ise() function, potentially leading to arbitrary code execution. This affects any systems or applications using the vulnerable astc-encoder library for texture compression.
💻 Affected Systems
- ARM astc-encoder
- Applications using astc-encoder library
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Remote code execution with the privileges of the process using astcenc, potentially leading to complete system compromise.
Likely Case
Application crash (denial of service) when processing maliciously crafted texture files.
If Mitigated
Limited impact if the vulnerable component runs in a sandboxed environment with minimal privileges.
🎯 Exploit Status
Proof of concept demonstrates crash via crafted texture file. Full RCE exploitation would require additional work but is feasible given the buffer overflow nature.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: astcenc 3.3.0 and later
Vendor Advisory: https://github.com/ARM-software/astc-encoder/issues/296
Restart Required: Yes
Instructions:
1. Download astcenc 3.3.0 or later from GitHub. 2. Replace the vulnerable astcenc binary. 3. Rebuild any applications using the astc-encoder library. 4. Restart affected services.
🔧 Temporary Workarounds
Disable -cl compression option
allAvoid using the -cl command-line option that triggers the vulnerable code path
Do not use '-cl' flag with astcenc
Input validation
allValidate texture files before processing with astcenc
🧯 If You Can't Patch
- Run astcenc in a sandboxed container with minimal privileges
- Implement network segmentation to isolate systems using astcenc
🔍 How to Verify
Check if Vulnerable:
Check astcenc version: 'astcenc --version' should show 3.2.0. Also check if applications use astcenc with -cl option.Check Version:
astcenc --versionVerify Fix Applied:
Verify astcenc version is 3.3.0 or later: 'astcenc --version'📡 Detection & Monitoring
Log Indicators:
- Application crashes when processing texture files
- Segmentation faults in astcenc processes
Network Indicators:
- Unusual file uploads to texture processing services
SIEM Query:
Process:astcenc AND (CommandLine:*cl* OR ExitCode:139 OR ExitCode:-1073741819)