Marlin Firmware 2.1.2.7 Out-of-Bounds Write via M421 G-code Handler
41Vexday Risk Score
No sign of exploitation. It has a public proof of concept.
ssvc Attendcvss 8.3epss 0.5%
from disclosure to weapon0 days
Published on NVDJun 24
1st PoCJun 24
exploitation probability
0.5%top 57% of all CVEs
observed exploitation
nono source reports it
2 public exploit(s)
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:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:H/VA:H/SC:N/SI:N/SA:N
Affected products
MarlinFirmware · Marlinpublic PoCs found — 2
githubgithub.com/Christbowel/CVE-2026-56111★ 1cve_referencegithub.com/MarlinFirmware/Marlin/issues/28467unverified⚠ Public resources, to assess the exposure of systems you control or are authorized to test. Test only with authorization.