CVE-2025-69209 - ArduinoCore-avr has Stack-Based Buffer Overflow in WString Float/Double Constructors

CVE-2025-69209 - ArduinoCore-avr has Stack-Based Buffer Overflow in WString Float/Double Constructors

https://cvefeed.io/rssfeed/latest.atom / Wed, 01/21/2026 - 22:58
CVE ID : CVE-2025-69209
Published : Jan. 21, 2026, 8:16 p.m. | 1 hour, 42 minutes ago
Description : 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](https://github.com/arduino/ArduinoCore-avr) - The Fixing Commit is available at the following link [1a6a417f89c8901dad646efce74ae9d3ddebfd59](https://github.com/arduino/ArduinoCore-avr/pull/613/commits/1a6a417f89c8901dad646efce74ae9d3ddebfd59) ### References - [ASEC-26-001 ArduinoCore-avr vXXXX Resolves Buffer Overflow Vulnerability](https://support.arduino.cc/hc/en-us/articles/XXXXX) ### Credits - Maxime Rossi Bellom and Ramtine Tofighi Shirazi from SecMate (https://secmate.dev/)
Severity: 6.9 | MEDIUM
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