CVE-2021-40400
📋 TL;DR
An out-of-bounds read vulnerability in Gerbv's RS-274X aperture macro outline primitive allows attackers to read memory beyond allocated buffers via specially crafted Gerber files. This can lead to information disclosure including potentially sensitive data from application memory. Users of Gerbv 2.7.0 and development versions are affected when processing untrusted Gerber files.
💻 Affected Systems
- Gerbv
- Forked Gerbv
📦 What is this software?
Gerbv by Gerbv Project
Gerbv by Gerbv Project
⚠️ Risk & Real-World Impact
Worst Case
Memory disclosure could reveal sensitive information like passwords, keys, or proprietary data from the application's memory space, potentially enabling further attacks.
Likely Case
Information disclosure of application memory contents, which could include file paths, configuration data, or other non-critical information from the Gerbv process.
If Mitigated
Limited impact with proper input validation and memory protections, potentially causing application instability or crashes.
🎯 Exploit Status
Exploitation requires the victim to open a malicious Gerber file. The vulnerability is in file parsing, so no authentication is needed beyond file access.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Check upstream repositories for fixes after the disclosure date (2021). The vulnerability was reported to the maintainers.
Vendor Advisory: https://talosintelligence.com/vulnerability_reports/TALOS-2021-1413
Restart Required: Yes
Instructions:
1. Update Gerbv to a patched version from official repositories. 2. For development versions, pull latest commits from upstream. 3. Recompile if using source. 4. Restart Gerbv after update.
🔧 Temporary Workarounds
Restrict Gerber file sources
allOnly process Gerber files from trusted sources. Implement file validation before opening in Gerbv.
Use alternative viewers
allTemporarily use alternative Gerber file viewers that are not affected by this vulnerability.
🧯 If You Can't Patch
- Implement strict file source controls - only open Gerber files from verified, trusted sources
- Run Gerbv in a sandboxed environment with limited memory access and network capabilities
🔍 How to Verify
Check if Vulnerable:
Check Gerbv version: gerbv --version. If version is 2.7.0 or development versions around 2021, you are likely vulnerable.Check Version:
gerbv --versionVerify Fix Applied:
Update to latest version and verify with gerbv --version. Test with known safe Gerber files to ensure functionality.📡 Detection & Monitoring
Log Indicators:
- Application crashes when opening Gerber files
- Unexpected memory access errors in system logs
Network Indicators:
- N/A - This is a local file processing vulnerability
SIEM Query:
Process execution: gerbv with suspicious file paths or from untrusted sources