{"id":"CVE-2026-56111","state":"PUBLISHED","title":"Marlin Firmware 2.1.2.7 Out-of-Bounds Write via M421 G-code Handler","description":"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.","publishedAt":"2026-06-24T14:31:04.284Z","updatedAt":"2026-07-28T01:49:41.086Z","severity":{"score":8.3,"label":"High","version":"4.0","vector":"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","source":"VulnCheck"},"assigner":"VulnCheck","products":["MarlinFirmware Marlin"],"affected":[{"vendor":"MarlinFirmware","product":"Marlin","packageURL":"pkg:github/MarlinFirmware/Marlin","defaultStatus":"affected","versions":[{"version":"0","status":"affected","lessThanOrEqual":"2.1.2.7","versionType":"custom"},{"version":"1f255d16ec2d456454fd444494cfb338d62b0fa1","status":"unaffected","versionType":"git"}],"repo":"https://github.com/MarlinFirmware/Marlin"}],"references":["https://github.com/MarlinFirmware/Marlin/issues/28467","https://github.com/MarlinFirmware/Marlin/pull/28468","https://github.com/MarlinFirmware/Marlin/commit/1f255d16ec2d456454fd444494cfb338d62b0fa1","https://www.vulncheck.com/advisories/marlin-firmware-out-of-bounds-write-via-m421-g-code-handler"],"weaknesses":["CWE-129"],"ingestedAt":"2026-10-29T20:12:24.861Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/56xxx/CVE-2026-56111.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-56111","state":"PUBLISHED","datePublished":"2026-06-24T14:31:04.284Z","dateUpdated":"2026-07-28T01:49:41.086Z","assignerShortName":"VulnCheck","assignerOrgId":"83251b91-4cc7-4094-a5c7-464a1b83ea10","dateReserved":"2026-06-18T19:15:10.650Z"},"containers":{"cna":{"title":"Marlin Firmware 2.1.2.7 Out-of-Bounds Write via M421 G-code Handler","descriptions":[{"lang":"en","value":"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. 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