CVE-2026-56111
Out-of-bounds write in Marlin M421 G-code handler enables DoS via crafted G-code.
Is CVE-2026-56111 being exploited?
Not confirmed. CVE-2026-56111 does not appear in CISA's Known Exploited Vulnerabilities catalog, which records only exploitation that has been observed and reported publicly. That is evidence of absence of a report, not evidence the flaw is unattacked. EPSS currently estimates a 0.65% probability of exploitation in the next 30 days.
How severe is CVE-2026-56111?
CVE-2026-56111 is rated High with a CVSS score of 8.3. Severity describes how bad exploitation would be, not how likely it is: pair it with exploitation evidence before deciding what to patch first.
Is there a patch for CVE-2026-56111?
Yes. A fix has been recorded for CVE-2026-56111. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2026-56111 affect?
CVE-2026-56111 affects Marlin Firmware 2.1.2.7 (MESH_BED_LEVELING). Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-56111?
Update to patched Marlin firmware containing the fix.
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
Attacker can corrupt firmware memory via crafted G-code sent over USB, network, or files, causing DoS or firmware state corruption.
Patch when possible
- affected<= 2.1.2.7
As published in the CVE Program record. A version outside these ranges is not a statement that it is unaffected — vendors sometimes understate a range, and distribution-backported builds carry upstream numbers that do not reflect what was patched into them.