CVE-2026-56111
Marlin Firmware 2.1.2.7 Out-of-Bounds Write via M421 G-code Handler
CVSS Score
9.1
EPSS Score
0.0%
EPSS Percentile
0th
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.
| CWE | CWE-129 |
| Vendor | marlinfirmware |
| Product | marlin |
| Published | Jun 24, 2026 |
| Last Updated | Jun 24, 2026 |
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CVSS v3 Breakdown
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
High
Availability
High
Affected Versions
MarlinFirmware / Marlin
0 ≤ 2.1.2.7
References
github.com: https://github.com/MarlinFirmware/Marlin/issues/28467 github.com: https://github.com/MarlinFirmware/Marlin/pull/28468 github.com: https://github.com/MarlinFirmware/Marlin/commit/1f255d16ec2d456454fd444494cfb338d62b0fa1 vulncheck.com: https://www.vulncheck.com/advisories/marlin-firmware-out-of-bounds-write-via-m421-g-code-handler
Credits
Christ Bouchuen