CVE-2026-56111 — Marlin Firmware 2.1.2.7 Out-of-Bounds Write via M421 G-code Handler
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 tha…
Published: 2026-06-24 · CVSS: 8.3 · CVSS 4.0
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.
Source: CVE Program · Revision 8b16575c39f1e1810c5e863010da073d2d3285e7