CVE-2025-69209

ArduinoCore-avr contains the source code and configuration files of the Arduino AVR Boards platform. A vulnerability in versions prior to 1.8.7 allows an attacker to trigger a stack-based buffer overflow when converting floating-point values to strings with high precision. By passing very large decimalPlaces values to the affected String constructors or concat methods, the dtostrf function writes beyond fixed-size stack buffers, causing memory corruption and denial of service. Under specific conditions, this could enable arbitrary code execution on AVR-based Arduino boards.

Patches

• The Fix is included starting from the 1.8.7 release available from the following link ArduinoCore-avr v1.8.7

• The Fixing Commit is available at the following link 1a6a417f89c8901dad646efce74ae9d3ddebfd59

References

• ASEC-26-001 ArduinoCore-avr vXXXX Resolves Buffer Overflow Vulnerability

Credits

• Maxime Rossi Bellom and Ramtine Tofighi Shirazi from SecMate (https://secmate.dev/)