CVE-2026-56111

Description

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.

References

https://www.vulncheck.com/advisories/marlin-firmware-out-of-bounds-write-via-m421-g-code-handler

https://github.com/MarlinFirmware/Marlin/pull/28468

https://github.com/MarlinFirmware/Marlin/issues/28467

https://github.com/MarlinFirmware/Marlin/commit/1f255d16ec2d456454fd444494cfb338d62b0fa1

Details

Source: Mitre, NVD

Risk Information

CVSS v2

CVSS v3

CVSS v4

EPSS