CVE-2026-56111
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.
INFO
Published Date :
June 24, 2026, 4:16 p.m.
Last Modified :
July 14, 2026, 10:17 p.m.
Remotely Exploit :
Yes !
Source :
[email protected]
Affected Products
The following products are affected by CVE-2026-56111
vulnerability.
Even if cvefeed.io is aware of the exact versions of the
products
that
are
affected, the information is not represented in the table below.
No affected product recoded yet
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS | 134c704f-9b21-4f2e-91b3-4a467353bcc0 | |||||
| CVSS 3.1 | CRITICAL | 83251b91-4cc7-4094-a5c7-464a1b83ea10 | ||||
| CVSS 3.1 | CRITICAL | [email protected] | ||||
| CVSS 4.0 | HIGH | 83251b91-4cc7-4094-a5c7-464a1b83ea10 | ||||
| CVSS 4.0 | HIGH | [email protected] |
Solution
- Update Marlin firmware to a version that includes commit 1f255d1.
- Ensure MESH_BED_LEVELING is disabled if updating is not possible.
Public PoC/Exploit Available at Github
CVE-2026-56111 has a 1 public
PoC/Exploit available at Github.
Go to the Public Exploits tab to see the list.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-56111.
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-56111 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-56111
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Proof of concept for CVE-2026-56111, an out-of-bounds write in the M421 G-code handler of Marlin Firmware
C
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-56111 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-56111 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
CVE Modified by [email protected]
Jul. 14, 2026
Action Type Old Value New Value Changed Affected [{'repo': 'https://github.com/MarlinFirmware/Marlin', 'vendor': 'MarlinFirmware', 'product': 'Marlin', 'versions': [{'status': 'affected', 'version': '0', 'versionType': 'custom', 'lessThanOrEqual': '2.1.2.7'}, {'status': 'unaffected', 'version': '1f255d16ec2d456454fd444494cfb338d62b0fa1', 'versionType': 'git'}], 'defaultStatus': 'affected'}] [{'repo': 'https://github.com/MarlinFirmware/Marlin', 'vendor': 'MarlinFirmware', 'product': 'Marlin', 'versions': [{'status': 'affected', 'version': '0', 'versionType': 'custom', 'lessThanOrEqual': '2.1.2.7'}, {'status': 'unaffected', 'version': '1f255d16ec2d456454fd444494cfb338d62b0fa1', 'versionType': 'git'}], 'packageURL': 'pkg:github/MarlinFirmware/Marlin', 'defaultStatus': 'affected'}] -
CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0
Jun. 24, 2026
Action Type Old Value New Value Added SSVC {'id': 'CVE-2026-56111', 'role': 'CISA Coordinator', 'options': [{'exploitation': 'poc'}, {'automatable': 'yes'}, {'technicalImpact': 'partial'}], 'version': '2.0.3', 'timestamp': '2026-06-24T15:52:16.839509Z'} -
New CVE Received by [email protected]
Jun. 24, 2026
Action Type Old Value New Value Added Affected [{'repo': 'https://github.com/MarlinFirmware/Marlin', 'vendor': 'MarlinFirmware', 'product': 'Marlin', 'versions': [{'status': 'affected', 'version': '0', 'versionType': 'custom', 'lessThanOrEqual': '2.1.2.7'}, {'status': 'unaffected', 'version': '1f255d16ec2d456454fd444494cfb338d62b0fa1', 'versionType': 'git'}], 'defaultStatus': 'affected'}] Added 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. Added CVSS V4.0 AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X Added CVSS V3.1 AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H Added CWE CWE-129 Added Reference https://github.com/MarlinFirmware/Marlin/commit/1f255d16ec2d456454fd444494cfb338d62b0fa1 Added Reference https://github.com/MarlinFirmware/Marlin/issues/28467 Added Reference https://github.com/MarlinFirmware/Marlin/pull/28468 Added Reference https://www.vulncheck.com/advisories/marlin-firmware-out-of-bounds-write-via-m421-g-code-handler