CVE-2020-18430
📋 TL;DR
CVE-2020-18430 is an array index error in tinyexr 0.9.5's DecodeEXRImage component that can cause denial of service through application crashes. This affects any application using the vulnerable tinyexr library to process EXR image files. Users and systems processing untrusted EXR files are at risk.
💻 Affected Systems
- tinyexr
📦 What is this software?
Tinyexr by Tinyexr Project
⚠️ Risk & Real-World Impact
Worst Case
Remote code execution if the array index error leads to memory corruption that can be controlled by an attacker, though this is not confirmed in the CVE description.
Likely Case
Denial of service through application crash when processing a malicious EXR file, disrupting service availability.
If Mitigated
No impact if proper input validation or patched versions are used, or if EXR file processing is restricted to trusted sources.
🎯 Exploit Status
Exploitation requires an attacker to provide a malicious EXR file; public proof-of-concept exists in GitHub references.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 0.9.6 or later
Vendor Advisory: https://github.com/syoyo/tinyexr/issues/108
Restart Required: Yes
Instructions:
1. Update tinyexr to version 0.9.6 or later. 2. Recompile any applications using tinyexr with the updated library. 3. Restart affected services or applications.
🔧 Temporary Workarounds
Disable EXR file processing
allPrevent applications from processing EXR files to avoid triggering the vulnerability.
Configure application settings to reject EXR files or disable tinyexr functionality if possible.
Input validation for EXR files
allImplement strict validation or sanitization of EXR files before processing with tinyexr.
Use file type verification tools or custom checks to ensure EXR files are from trusted sources.
🧯 If You Can't Patch
- Restrict access to EXR file uploads or processing to trusted users only.
- Monitor systems for crashes or anomalies related to image processing and investigate promptly.
🔍 How to Verify
Check if Vulnerable:
Check the tinyexr version in use; if it is 0.9.5, the system is vulnerable. Use 'ldd' or dependency checks on applications to verify tinyexr linkage.Check Version:
For compiled applications, check build logs or use 'strings' on binaries to find tinyexr version strings; for source, inspect version headers.Verify Fix Applied:
Confirm tinyexr version is 0.9.6 or later after update, and test with known malicious EXR files to ensure no crashes occur.📡 Detection & Monitoring
Log Indicators:
- Application crashes or segmentation faults when processing EXR files.
- Error logs mentioning tinyexr or DecodeEXRImage failures.
Network Indicators:
- Unusual uploads of EXR files to web applications or services.
SIEM Query:
Example: search for 'tinyexr' OR 'EXR' in application logs with error or crash events.