CVE-2021-3510
📋 TL;DR
This vulnerability in Zephyr's JSON decoder allows attackers to cause memory corruption by exploiting incorrect array-of-array decoding. It affects Zephyr RTOS users running vulnerable versions, potentially leading to denial of service or arbitrary code execution. The flaw exists when processing specially crafted JSON input.
💻 Affected Systems
- Zephyr RTOS
📦 What is this software?
Zephyr by Zephyrproject
Zephyr by Zephyrproject
Zephyr by Zephyrproject
Zephyr by Zephyrproject
Zephyr by Zephyrproject
Zephyr by Zephyrproject
Zephyr by Zephyrproject
Zephyr by Zephyrproject
Zephyr by Zephyrproject
Zephyr by Zephyrproject
Zephyr by Zephyrproject
Zephyr by Zephyrproject
Zephyr by Zephyrproject
Zephyr by Zephyrproject
Zephyr by Zephyrproject
Zephyr by Zephyrproject
Zephyr by Zephyrproject
Zephyr by Zephyrproject
Zephyr by Zephyrproject
Zephyr by Zephyrproject
Zephyr by Zephyrproject
Zephyr by Zephyrproject
⚠️ Risk & Real-World Impact
Worst Case
Remote code execution leading to complete system compromise, device takeover, or persistent backdoor installation
Likely Case
Denial of service through system crashes or reboots, potentially with memory corruption leading to unpredictable behavior
If Mitigated
Limited impact with proper input validation and memory protection mechanisms in place
🎯 Exploit Status
Exploitation requires sending specially crafted JSON to vulnerable JSON parsing functionality
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Fixed in Zephyr versions after the advisory publication
Vendor Advisory: https://github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-289f-7mw3-2qf4
Restart Required: Yes
Instructions:
1. Update Zephyr RTOS to patched version. 2. Rebuild and redeploy affected firmware. 3. Test JSON functionality after update.
🔧 Temporary Workarounds
Input validation and sanitization
allImplement strict JSON schema validation and input sanitization before passing to Zephyr JSON parser
Disable JSON parsing if unused
allRemove or disable JSON parsing functionality if not required for device operation
🧯 If You Can't Patch
- Implement network segmentation to isolate vulnerable devices
- Deploy application firewalls to filter and validate JSON input before reaching vulnerable systems
🔍 How to Verify
Check if Vulnerable:
Check Zephyr version against affected ranges: >=1.14.0 or >=2.5.0Check Version:
Check Zephyr build configuration or firmware version informationVerify Fix Applied:
Verify Zephyr version is updated beyond vulnerable ranges and test JSON parsing with edge cases📡 Detection & Monitoring
Log Indicators:
- System crashes during JSON processing
- Memory corruption errors in system logs
- Unexpected reboots after JSON input
Network Indicators:
- Malformed JSON payloads to device APIs
- Unusual JSON structure patterns in network traffic
SIEM Query:
source="device_logs" AND ("segmentation fault" OR "memory corruption" OR "panic") AND "json"