Buffer overflow in Arduino Arduinocore-Avr

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](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/)

Vulnerability class: Buffer Overflow

Published · last modified .

EPSS exploit prediction

EPSS: 0.002 (6.1th percentile), scored .

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 6th percentile — 6.1% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS trend (30 days)EPSS over the last 30 days for CVE-2025-69209: held from 0.002 to 0.002.

EPSS over last 30 days · oldest: 0.002 · newest: 0.002 · change: +0.000

Affected products

Weakness classification (CWE)

References