CVE-2026-56111

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.

CVSS v3 9.1 CRITICAL

9.1^/10

CVSS v3 : CRITICAL

Vector :

Exploitability : 3.9 / Impact : 5.2

Attack Vector NETWORK

Attack Complexity LOW

Privileges Required NONE

User Interaction NONE

Confidentiality Impact NONE

Integrity Impact HIGH

Availability Impact HIGH

Scope UNCHANGED

References

Link	Resource
https://github.com/MarlinFirmware/Marlin/commit/1f255d16ec2d456454fd444494cfb338d62b0fa1
https://github.com/MarlinFirmware/Marlin/issues/28467
https://github.com/MarlinFirmware/Marlin/pull/28468
https://www.vulncheck.com/advisories/marlin-firmware-out-of-bounds-write-via-m421-g-code-handler

Configurations

No configuration.

History

24 Jun 2026, 16:16

Type	Values Removed	Values Added
New CVE

Information

Published : 2026-06-24 16:16

Updated : 2026-06-25 19:25

NVD link : CVE-2026-56111

Mitre link : CVE-2026-56111

CVE.ORG link : CVE-2026-56111

JSON object : View

Products Affected

No product.

CWE

CWE-129

Improper Validation of Array Index

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