CVE-2026-56111 Details
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.
A memory corruption vulnerability allowing out-of-bounds writes has been identified in Marlin Firmware versions through 2.1.2.7, when built with MESH_BED_LEVELING enabled. The issue resides in the M421 G-code handler for Mesh Bed Leveling, which fails to properly validate the I and J indices before writing to the mesh. This oversight allows attackers to send crafted G-code commands that write a 32-bit float value beyond the bounds of the z_values array, corrupting adjacent firmware variables. The exploitation of this vulnerability can lead to a denial-of-service condition or corruption of the firmware state. The flaw can be triggered by sending a single G-code command via USB serial, network interface, or a malicious G-code file.
Users can update to Marlin Firmware version 2.1.2.8 or later, where this vulnerability has been fixed.
Metrics
CVSS 4.0 Severity and Vector Strings:
CVSS 3.x Severity and Vector Strings:
No data available for CVSS Version 2.0 on this CVE.
CISA-ADP
Assessed Jun 24, 2026References to Advisories, Solutions, and Tools
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Weakness Enumeration
| CWE-ID | CWE Name | Source |
|---|---|---|
| CWE-129 | Improper Validation of Array Index | [email protected] |
Affected Products
No affected product data is available for this CVE.
Change History
3 change records found show changes
| Date | Action | Recorded By |
|---|---|---|
| Jul 14, 2026 | CVE Modified | [email protected] |
| Jun 24, 2026 | CVE Modified | CISA-ADP |
| Jun 24, 2026 | New CVE Received | [email protected] |