PT-2026-51836 · Marlinfirmware · Marlin

Christ Bouchuen · Published 2026-06-24 · Updated 2026-06-24 · CVE-2026-56111

Mitre

CVSS v3.1

9.1

Critical

Base vector

AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H

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.

Exploit

Fix

Improper Validation of Array Index

Weakness Enumeration

CWE-129

Related Identifiers

CVE-2026-56111

Affected Products

Marlin

References · 5

• 🔥 https://github.com/MarlinFirmware/Marlin/issues/28467 · Exploit
• https://nvd.nist.gov/vuln/detail/CVE-2026-56111 · Security Note
• https://github.com/MarlinFirmware/Marlin/commit/1f255d16ec2d456454fd444494cfb338d62b0fa1 · Patch
• https://vulncheck.com/advisories/marlin-firmware-out-of-bounds-write-via-m421-g-code-handler · Note
• https://github.com/MarlinFirmware/Marlin/pull/28468 · Note