Cyber Resilience

CVE-2026-56111

HighPublic PoC

Published: 24 June 2026

Published
24 June 2026
Modified
25 June 2026
KEV Added
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Patch
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CVSS Score v4 8.3 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/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
EPSS Score 0.0054 41.5th percentile
Risk Priority 55 floored blend · peak EPSS

Summary

CVE-2026-56111 is a high-severity Improper Validation of Array Index (CWE-129) vulnerability. Its CVSS base score is 8.3 (High).

Operationally, exploitation aligns with the MITRE ATT&CK technique Exploit Public-Facing Application (T1190); ranked at the 41.5th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog; a public proof-of-concept is referenced.

OWASP Top 10 for Web (2025)

A05:2025 Injection

EU & UK References

Vulnerability 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…

more

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.

CWE(s)
CWE-129

Related Threats

MITRE ATT&CK Enterprise TechniquesAI

T1190 Exploit Public-Facing Application Initial Access
Adversaries may attempt to exploit a weakness in an Internet-facing host or system to initially access a network.
attack.mitre.org →
T1204.002 Malicious File Execution
An adversary may rely upon a user opening a malicious file in order to gain execution.
attack.mitre.org →
Why these techniques?

OOB write in G-code handler directly enables exploitation via network-exposed interface (T1190) or malicious .gcode file (T1204.002).

Confidence: MEDIUM · MITRE ATT&CK Enterprise v19.0

Affected Assets

Mitigating Controls

No mitigating controls mapped yet. The per-CVE control annotator has not reached this CVE.

References