CVE-2026-56111
CriticalCVSS 9.1Exploitation Probability (EPSS)
Low risk42th percentile - higher than 42% of all known CVEs
Summary
Marlin Firmware up to version 2.1.2.7 (fixed in commit 1f255d1) has an out-of-bounds write vulnerability in the M421 G-code handler when MESH_BED_LEVELING is enabled. Attackers can send a crafted G-code command via USB serial, network interface, or malicious gcode file to write a controlled 32-bit float value past the z_values array bounds, corrupting firmware memory.
Risk Assessment
The risk includes Denial of Service (DoS) or permanent firmware state corruption, which can disrupt 3D printer operation and potentially allow further attack escalation.
Recommendation
Immediately update Marlin firmware to a version containing commit 1f255d1 or later. If updating is not possible, restrict access to USB and network interfaces and avoid running untrusted G-code files.
Original NVD description (English source)
Marlin Firmware through 2.1.2.7, fixed in commit 1f255d1, when built with MESH_BED_LEVELING enabled, contains an out-of-bounds write vulnerability in the M421 G-code handler that allows attackers to corrupt firmware memory by supplying out-of-range X and Y grid indices. Attackers can send a single crafted G-code command via USB serial, network interface, or malicious gcode file to write an attacker-controlled 32-bit float value past the z_values array bounds, corrupting adjacent firmware variables and causing denial of service or firmware state corruption.