CVE-2021-33388
📋 TL;DR
CVE-2021-33388 is a heap buffer overflow vulnerability in dpic's makevar() function that allows attackers to execute arbitrary code or cause denial of service. This affects users of dpic 2021.04.10 who process untrusted input files. The vulnerability is particularly dangerous because dpic is often used to process diagrams from various sources.
💻 Affected Systems
- dpic
📦 What is this software?
Dpic by Dpic Project
⚠️ Risk & Real-World Impact
Worst Case
Remote code execution leading to complete system compromise, data theft, or ransomware deployment.
Likely Case
Application crash (denial of service) when processing malicious input files.
If Mitigated
Limited impact if proper input validation and sandboxing are implemented.
🎯 Exploit Status
The vulnerability is in a core parsing function and requires only a malicious input file to trigger.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 2021.04.11 or later
Vendor Advisory: https://gitlab.com/aplevich/dpic/-/issues/8
Restart Required: No
Instructions:
1. Download latest dpic version from official repository. 2. Compile and install according to documentation. 3. Replace existing dpic binary with patched version.
🔧 Temporary Workarounds
Input validation and sandboxing
linuxRun dpic in a sandboxed environment and validate all input files before processing.
# Use bubblewrap or similar sandboxing tools
bwrap --unshare-all --share-net --ro-bind / / --bind /tmp /tmp dpic input.pic
🧯 If You Can't Patch
- Restrict dpic usage to trusted users only and implement strict file upload controls.
- Monitor for abnormal process crashes and implement application allowlisting.
🔍 How to Verify
Check if Vulnerable:
Check dpic version: dpic --version | grep '2021.04.10'Check Version:
dpic --versionVerify Fix Applied:
Verify version is 2021.04.11 or later: dpic --version📡 Detection & Monitoring
Log Indicators:
- Segmentation fault errors in system logs
- Abnormal dpic process termination
Network Indicators:
- Unusual file uploads to systems using dpic
SIEM Query:
process_name:dpic AND (event_type:crash OR exit_code:139)