CVE-2025-69209
📋 TL;DR
A stack-based buffer overflow vulnerability in ArduinoCore-avr allows attackers to trigger memory corruption by passing large decimalPlaces values when converting floating-point values to strings. This can cause denial of service and potentially enable arbitrary code execution on AVR-based Arduino boards. Users of Arduino boards with affected ArduinoCore-avr versions are impacted.
💻 Affected Systems
- ArduinoCore-avr
⚠️ Manual Verification Required
This CVE does not have specific version information in our database, so automatic vulnerability detection cannot determine if your system is affected.
Why? The CVE database entry doesn't specify which versions are vulnerable (no version ranges provided by the vendor/NVD).
🔒 Custom verification scripts are available for registered users. Sign up free to download automated test scripts.
- Review the CVE details at NVD
- Check vendor security advisories for your specific version
- Test if the vulnerability is exploitable in your environment
- Consider updating to the latest version as a precaution
⚠️ Risk & Real-World Impact
Worst Case
Arbitrary code execution on AVR-based Arduino boards, allowing full device compromise and potential lateral movement in connected systems.
Likely Case
Denial of service through device crashes or instability when processing malicious floating-point conversions.
If Mitigated
Limited impact with proper input validation and updated libraries, though legacy devices may remain vulnerable.
🎯 Exploit Status
Exploitation requires ability to pass malicious input to affected String methods, which could occur through network interfaces or serial input.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 1.8.7
Vendor Advisory: https://github.com/arduino/ArduinoCore-avr/security/advisories/GHSA-pvx3-fm7w-6hjm
Restart Required: No
Instructions:
1. Open Arduino IDE. 2. Go to Tools > Board > Boards Manager. 3. Search for 'Arduino AVR Boards'. 4. Update to version 1.8.7 or later. 5. Recompile and upload sketches to affected boards.
🔧 Temporary Workarounds
Input Validation
allManually validate decimalPlaces parameter in code before passing to String constructors or concat methods.
// Example: Validate decimalPlaces before use
if (decimalPlaces > 10) { decimalPlaces = 10; } // Limit to safe value
🧯 If You Can't Patch
- Isolate Arduino devices on separate network segments with strict access controls.
- Implement input sanitization for all data entering Arduino systems, especially from untrusted sources.
🔍 How to Verify
Check if Vulnerable:
Check Arduino IDE: File > Preferences, note 'More preferences can be edited...' path, then check packages/arduino/hardware/avr/version.txt for version <1.8.7.Check Version:
grep -r 'version=' ~/.arduino15/packages/arduino/hardware/avr/boards.txt | head -1Verify Fix Applied:
Confirm Arduino AVR Boards version is 1.8.7 or higher in Boards Manager.📡 Detection & Monitoring
Log Indicators:
- Unexpected Arduino board resets
- Serial monitor showing abnormal floating-point conversion errors
Network Indicators:
- Unusual serial or network traffic to Arduino devices with large numeric parameters
SIEM Query:
device_vendor:"Arduino" AND (event_type:"crash" OR event_type:"reset") AND process_name:"String"🔗 References
- https://github.com/arduino/ArduinoCore-avr/commit/82a8ad2fb33911d8927c7af22e0472b94325d1a7
- https://github.com/arduino/ArduinoCore-avr/pull/613
- https://github.com/arduino/ArduinoCore-avr/releases/tag/1.8.7
- https://github.com/arduino/ArduinoCore-avr/security/advisories/GHSA-pvx3-fm7w-6hjm
- https://support.arduino.cc/hc/en-us/articles/24985906702748-ASEC-26-001-ArduinoCore-AVR-v1-8-7-Resolves-Stack-Based-Buffer-Overflow-Vulnerability
