{"id":"CVE-2026-56111","summary":"Marlin Firmware 2.1.2.7 Out-of-Bounds Write via M421 G-code Handler","details":"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.","modified":"2026-07-16T03:48:41.433704059Z","published":"2026-06-24T14:31:04.284Z","database_specific":{"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/56xxx/CVE-2026-56111.json","cna_assigner":"VulnCheck","cwe_ids":["CWE-129"]},"references":[{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/56xxx/CVE-2026-56111.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-56111"},{"type":"ADVISORY","url":"https://www.vulncheck.com/advisories/marlin-firmware-out-of-bounds-write-via-m421-g-code-handler"},{"type":"REPORT","url":"https://github.com/MarlinFirmware/Marlin/pull/28468"},{"type":"FIX","url":"https://github.com/MarlinFirmware/Marlin/commit/1f255d16ec2d456454fd444494cfb338d62b0fa1"},{"type":"PACKAGE","url":"https://github.com/MarlinFirmware/Marlin"},{"type":"EVIDENCE","url":"https://github.com/MarlinFirmware/Marlin/issues/28467"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/marlinfirmware/marlin","events":[{"introduced":"0"},{"fixed":"3b8ab730b259e1388646050855aa133c85a077cb"},{"fixed":"1f255d16ec2d456454fd444494cfb338d62b0fa1"}],"database_specific":{"source":["DESCRIPTION","REFERENCES"],"extracted_events":[{"introduced":"0"},{"fixed":"2.1.2.7"}]}}],"versions":["2.1.2.6","dev-2.1.3-b3","dev-2.1.3-b2","2.1.2.5","dev-2.1.3-b1","2.1.2.4","2.1.2.3","2.1.2.2","2.1.2.1","2.0.0","2.0.1","2.0.4.4","2.0.5.4","2.0.6.1","2.0.7.2","2.0.8.2","2.1.1","2.1","2.1.2","2.0.9.4","2.0.9.3","2.0.9.2","2.0.9.1","2.0.9","2.0.8.1","2.0.8","2.0.7.1","2.0.7","2.0.6","2.0.5.3","2.0.5.2","2.0.5.1","2.0.5","2.0.4.3","2.0.4.2","2.0.4.1","2.0.4","1.1.0-RC3","1.1.0-RC4","1.0.1","1.0.0-beta"],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-56111.json"}}],"schema_version":"1.7.5","severity":[{"type":"CVSS_V4","score":"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"}]}