CVE-2026-56111

CRITICALPre-NVD 9.19.1
EchelonGraph scoreMEDIUM confidence

“—” beside the score: it is equal to the CVSS score beside it.

Score 9.1 from GitHub Security Advisory (severity: HIGH) published 2026-06-24. A secondary CVSS source baseline 9.1; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: EPSS, GitHub Security Advisory, a secondary CVSS source
Trending — 3 sources updated this weekElevated

Also known asEUVD-2026-38797 (ENISA EUVD) · GHSA-x5qg-qgv8-q7cr (GitHub Security Advisories)Source: ENISA EUVD

9.1EG
EchelonGraph verdictPlan mitigationRemediate within your standard update timelines at low or medium mission impact and sooner than that at high (the SSVC decision on this page).
  • CISA's Vulnrichment rates exploitation as PoC; EchelonGraph holds no exploit-code reference for it
CISA-KEV: Not listedEPSS PROB: 0.6%CVSS: 9.1Exploit: No code on recordExposed services: Not assessed

An upstream fix is merged but not yet released — mitigate (WAF / firewall / segmentation) until the release ships, then apply it.

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.

CVSS v3
9.1
EG Score
9.1CRITICALmedium confidence
EG Risk
72
EG Risk 72/100

EG Risk is EchelonGraph's 0–100 priority score. It fuses impact severity (EG Severity, the CVSS base score, never the KEV-floored or EPSS-lifted EG Score) with real-world exploitation and automatability, under weights EchelonGraph set by hand, so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner.

How it’s computed (value × EchelonGraph’s weight)
Severity91% × 45%
Impact severity (EG Severity): CVSS 9.1 of 10. Never the KEV-floored or EPSS-lifted EG Score.
Exploitation40% × 40%
EchelonGraph's fixed weight for EG-KEV Tier 3 (Elevated): a constant, not a probability.
Automatability100% × 15%
CISA's SSVC Automatable value: yes (Vulnrichment).
SSVC (CISA's decision table, applied by EchelonGraph): Track at low or medium mission impact; Attend at high (mission-essential systems).
Exploitation public PoC (CISA Vulnrichment) · Automatable yes (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE.
Action: An upstream fix is merged but not yet in a tagged release. Restrict network exposure of the affected system or apply the vendor's mitigation within your standard update timelines at low or medium mission impact and sooner than that at high until it ships, then apply the release.
EPSS PROB
0.6%
EPSS %ILE
50th
KEV
Not listed

What the EG score is made of (scorer v4.0: the three questions the 0–10 score mixes, published apart · methodology)

The EG score (9.1): severity, escalated by confirmed exploitation. This CVE's 9.1 is its impact severity (EG Severity), not escalated.

EG Severity
9.1 CRITICALCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.GitHub Security Advisory CVSS
EG Likelihood
0.6% within 30 daysSource: FIRST EPSS (model v2026.06.15, score date 2026-10-26). FIRST's exploitation probability, not an EchelonGraph model.
Confirmed exploitation
None on record (CISA KEV, EG-KEV Tier 1)Reported apart from the likelihood: an observed fact, not a probability.
EG Priority
SSVC Track at medium mission impactTrack at low or medium mission impact; Attend at high (mission-essential systems).CISA BOD 26-04: 14 days if the affected system is publicly exposed; 60 days if it is not.Each input and its source: the SSVC and BOD 26-04 blocks below.

SSVC (CISA's decision table, applied by EchelonGraph)Track at low or medium mission impact; Attend at high (mission-essential systems).

An upstream fix is merged but not yet in a tagged release. Restrict network exposure of the affected system or apply the vendor's mitigation within your standard update timelines at low or medium mission impact and sooner than that at high until it ships, then apply the release.

Exploitation public PoC (CISA Vulnrichment) · Automatable yes (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE. Mission impact is CISA's Mission & Well-being decision point, and only you can judge it. CISA's table makes it high when Mission Prevalence is Essential — the vulnerable component "directly provides capabilities that constitute at least one MEF for at least one entity" (MEF: mission essential function) — or when Public Well-Being Impact is Irreversible: "multiple fatalities are likely", the cyber-physical system "is likely lost or destroyed", "extreme or serious externalities" are imposed on other parties, or social systems such as elections or the financial grid "are destabilized and potentially collapse". CISA's decision table

BOD 26-04 (CISA's remediation timeline, Table 1)14 days if the affected system is publicly exposed; 60 days if it is not.

In CISA KEV no (CISA's KEV catalog) · Automatable yes (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). Whether your system is publicly exposed is yours to answer. BOD 26-04 binds US Federal Civilian Executive Branch agencies; for anyone else it is CISA's published timeline, a reference rather than an obligation. The directive · how EchelonGraph applies it

Published

June 24, 2026

Last Modified

October 25, 2026

Advisory Details (4)

Auto-updated Sep 16, 2026
Upstream fix merged — awaiting tagged release. Sources: github_pr, github_commit.
Web page

Marlin Firmware 2.1.2.7 Out-of-Bounds Write via M421 G-code Handler | Advisories | VulnCheck

https://www.vulncheck.com/advisories/marlin-firmware-out-of-bounds-write-via-m421-g-code-handler
GitHub commit

commit 1f255d16ec2d (MarlinFirmware/Marlin)

Fix landed in MarlinFirmware/Marlin commit 1f255d16ec2d — awaiting tagged release

https://github.com/MarlinFirmware/Marlin/commit/1f255d16ec2d456454fd444494cfb338d62b0fa1
GitHub pull request

Bound-check I/J indices in M421 (Mesh Bed Leveling)

Fix merged in MarlinFirmware/Marlin PR #28468 on 2026-06-23 — awaiting tagged release

https://github.com/MarlinFirmware/Marlin/pull/28468
Web page

[BUG] M421 (Mesh Bed Leveling) accepts out-of-range I/J indices, unlike the ABL and UBL variants · Issue #28467 · MarlinFirmware/Marlin · GitHub

https://github.com/MarlinFirmware/Marlin/issues/28467

Vendor Advisories for CVE-2026-56111(1)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 23× in last 7d / 67× in last 30d)

Each row is a time one of our pipelines fetched, updated or re-scored this CVE. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. An arrow marks a change the record states ("CVSS v3 → 9.1"); EPSS and GHSA rows show the values recorded at that time, not what changed (EPSS values are rounded; hover one for the exact figures). Most recent first.

Showing the most recent 100 of 506 refreshes on record for this CVE.

A repeat, a row identical to one the same pipeline wrote less than 10 seconds earlier, is not a separate refresh and is not counted. None are among the latest 100 rows. The 406 oldest rows on record are not shown and were not checked, so the counts can still include repeats.

  1. 2026-10-27 16:32 UTCEPSS rescoreEPSS 0.6% · 50th percentile
  2. 2026-10-27 12:59 UTCGHSA enrichmentGHSA-x5qg-qgv8-q7cr · GitHub severity HIGH · GitHub CVSS 9.1
  3. 2026-10-27 00:56 UTCEG score recompute
  4. 2026-10-27 00:56 UTCGHSA enrichmentGHSA-x5qg-qgv8-q7cr · GitHub severity HIGH · GitHub CVSS 9.1
  5. 2026-10-26 16:31 UTCEPSS rescoreEPSS 0.6% · 50th percentile
  6. 2026-10-25 22:26 UTCEG score recompute
  7. 2026-10-25 22:26 UTCGHSA enrichmentGHSA-x5qg-qgv8-q7cr · GitHub severity HIGH · GitHub CVSS 9.1
  8. 2026-10-25 16:33 UTCEPSS rescoreEPSS 0.6% · 50th percentile
  9. 2026-10-25 14:18 UTCEG score recompute
  10. 2026-10-25 05:07 UTCEG score recompute
  11. 2026-10-25 05:07 UTCGHSA enrichmentGHSA-x5qg-qgv8-q7cr · GitHub severity HIGH · GitHub CVSS 9.1
  12. 2026-10-24 16:33 UTCEPSS rescoreEPSS 0.6% · 50th percentile
  13. 2026-10-24 06:21 UTCEG score recompute
  14. 2026-10-24 06:21 UTCGHSA enrichmentGHSA-x5qg-qgv8-q7cr · GitHub severity HIGH · GitHub CVSS 9.1
  15. 2026-10-23 16:32 UTCEPSS rescoreEPSS 0.6% · 50th percentile
  16. 2026-10-23 07:33 UTCEG score recompute
  17. 2026-10-23 07:32 UTCGHSA enrichmentGHSA-x5qg-qgv8-q7cr · GitHub severity HIGH · GitHub CVSS 9.1
  18. 2026-10-22 16:34 UTCEPSS rescoreEPSS 0.6% · 50th percentile
  19. 2026-10-22 08:43 UTCEG score recompute
  20. 2026-10-22 08:43 UTCGHSA enrichmentGHSA-x5qg-qgv8-q7cr · GitHub severity HIGH · GitHub CVSS 9.1
  21. 2026-10-21 16:33 UTCEPSS rescoreEPSS 0.6% · 50th percentile
  22. 2026-10-21 09:57 UTCEG score recompute
  23. 2026-10-21 09:57 UTCGHSA enrichmentGHSA-x5qg-qgv8-q7cr · GitHub severity HIGH · GitHub CVSS 9.1
  24. 2026-10-20 16:33 UTCEPSS rescoreEPSS 0.6% · 50th percentile
  25. 2026-10-20 11:10 UTCEG score recompute
Show 75 more
  1. 2026-10-20 11:09 UTCGHSA enrichmentGHSA-x5qg-qgv8-q7cr · GitHub severity HIGH · GitHub CVSS 9.1
  2. 2026-10-19 16:32 UTCEPSS rescoreEPSS 0.6% · 50th percentile
  3. 2026-10-19 12:23 UTCEG score recompute
  4. 2026-10-19 12:22 UTCGHSA enrichmentGHSA-x5qg-qgv8-q7cr · GitHub severity HIGH · GitHub CVSS 9.1
  5. 2026-10-18 16:32 UTCEPSS rescoreEPSS 0.6% · 49th percentile
  6. 2026-10-18 10:37 UTCGHSA enrichmentGHSA-x5qg-qgv8-q7cr · GitHub severity HIGH · GitHub CVSS 9.1
  7. 2026-10-18 03:29 UTCEG score recompute
  8. 2026-10-17 16:34 UTCEPSS rescoreEPSS 0.6% · 49th percentile
  9. 2026-10-17 11:51 UTCEG score recompute
  10. 2026-10-17 11:51 UTCGHSA enrichmentGHSA-x5qg-qgv8-q7cr · GitHub severity HIGH · GitHub CVSS 9.1
  11. 2026-10-16 16:42 UTCEPSS rescoreEPSS 0.6% · 49th percentile
  12. 2026-10-16 13:04 UTCEG score recompute
  13. 2026-10-16 13:03 UTCGHSA enrichmentGHSA-x5qg-qgv8-q7cr · GitHub severity HIGH · GitHub CVSS 9.1
  14. 2026-10-15 16:32 UTCEPSS rescoreEPSS 0.6% · 49th percentile
  15. 2026-10-15 14:15 UTCEG score recompute
  16. 2026-10-15 14:15 UTCGHSA enrichmentGHSA-x5qg-qgv8-q7cr · GitHub severity HIGH · GitHub CVSS 9.1
  17. 2026-10-14 16:33 UTCEPSS rescoreEPSS 0.6% · 49th percentile
  18. 2026-10-14 08:59 UTCEG score recompute
  19. 2026-10-14 08:59 UTCGHSA enrichmentGHSA-x5qg-qgv8-q7cr · GitHub severity HIGH · GitHub CVSS 9.1
  20. 2026-10-13 16:34 UTCEPSS rescoreEPSS 0.6% · 49th percentile
  21. 2026-10-13 05:37 UTCEG score recompute
  22. 2026-10-13 05:37 UTCGHSA enrichmentGHSA-x5qg-qgv8-q7cr · GitHub severity HIGH · GitHub CVSS 9.1
  23. 2026-10-12 16:34 UTCEPSS rescoreEPSS 0.6% · 49th percentile
  24. 2026-10-12 15:55 UTCEG score recompute
  25. 2026-10-12 06:50 UTCGHSA enrichmentGHSA-x5qg-qgv8-q7cr · GitHub severity HIGH · GitHub CVSS 9.1
  26. 2026-10-11 19:38 UTCEG score recompute
  27. 2026-10-11 16:53 UTCEG score recompute
  28. 2026-10-11 14:16 UTCEG score recompute
  29. 2026-10-11 13:49 UTCEPSS rescoreEPSS 0.6% · 49th percentile
  30. 2026-10-10 20:00 UTCEPSS rescoreEPSS 0.6% · 49th percentile
  31. 2026-10-09 20:07 UTCEPSS rescoreEPSS 0.6% · 49th percentile
  32. 2026-10-08 17:13 UTCEPSS rescoreEPSS 0.6% · 49th percentile
  33. 2026-10-07 23:48 UTCEPSS rescoreEPSS 0.6% · 49th percentile
  34. 2026-10-06 15:18 UTCEPSS rescoreEPSS 0.6% · 49th percentile
  35. 2026-10-05 17:43 UTCEPSS rescoreEPSS 0.6% · 49th percentile
  36. 2026-10-04 23:22 UTCEPSS rescoreEPSS 0.6% · 49th percentile
  37. 2026-10-03 14:26 UTCEPSS rescoreEPSS 0.6% · 49th percentile
  38. 2026-10-02 17:56 UTCEPSS rescoreEPSS 0.6% · 49th percentile
  39. 2026-10-01 19:50 UTCEPSS rescoreEPSS 0.6% · 49th percentile
  40. 2026-09-30 15:03 UTCEPSS rescoreEPSS 0.6% · 49th percentile
  41. 2026-09-29 15:22 UTCEPSS rescoreEPSS 0.6% · 48th percentile
  42. 2026-09-28 13:51 UTCEPSS rescoreEPSS 0.6% · 48th percentile
  43. 2026-09-27 13:48 UTCEPSS rescoreEPSS 0.6% · 48th percentile
  44. 2026-09-26 15:59 UTCEPSS rescoreEPSS 0.6% · 48th percentile
  45. 2026-09-24 14:04 UTCEPSS rescoreEPSS 0.6% · 48th percentile
  46. 2026-09-23 17:54 UTCEPSS rescoreEPSS 0.6% · 49th percentile
  47. 2026-09-23 11:47 UTCEG score recompute
  48. 2026-09-23 11:47 UTCGHSA enrichmentGHSA-x5qg-qgv8-q7cr · GitHub severity HIGH · GitHub CVSS 9.1
  49. 2026-09-20 20:16 UTCEPSS rescoreEPSS 0.6% · 49th percentile
  50. 2026-09-18 19:28 UTCEPSS rescoreEPSS 0.6% · 49th percentile
  51. 2026-09-18 08:09 UTCEG score recompute
  52. 2026-09-18 08:09 UTCGHSA enrichmentGHSA-x5qg-qgv8-q7cr · GitHub severity HIGH · GitHub CVSS 9.1
  53. 2026-09-17 19:31 UTCEPSS rescoreEPSS 0.6% · 49th percentile
  54. 2026-09-16 14:08 UTCEPSS rescoreEPSS 0.6% · 49th percentile
  55. 2026-09-16 05:15 UTCEPSS rescoreEPSS 0.6% · 49th percentile
  56. 2026-09-15 03:11 UTCEPSS rescoreEPSS 0.6% · 49th percentile
  57. 2026-09-14 09:37 UTCGHSA enrichmentGHSA-x5qg-qgv8-q7cr · GitHub severity HIGH · GitHub CVSS 9.1
  58. 2026-09-14 05:48 UTCGHSA enrichmentGHSA-x5qg-qgv8-q7cr · GitHub severity HIGH · GitHub CVSS 9.1
  59. 2026-09-14 01:57 UTCEG score recompute
  60. 2026-09-14 01:57 UTCGHSA enrichmentGHSA-x5qg-qgv8-q7cr · GitHub severity HIGH · GitHub CVSS 9.1
  61. 2026-09-13 16:47 UTCEPSS rescoreEPSS 0.6% · 49th percentile
  62. 2026-09-13 12:02 UTCEG score recompute
  63. 2026-09-13 12:01 UTCGHSA enrichmentGHSA-x5qg-qgv8-q7cr · GitHub severity HIGH · GitHub CVSS 9.1
  64. 2026-09-11 14:53 UTCEPSS rescoreEPSS 0.6% · 48th percentile
  65. 2026-09-10 09:35 UTCEPSS rescoreEPSS 0.6% · 48th percentile
  66. 2026-09-08 22:01 UTCEPSS rescoreEPSS 0.6% · 48th percentile
  67. 2026-09-07 16:01 UTCEPSS rescoreEPSS 0.6% · 48th percentile
  68. 2026-09-06 13:47 UTCEPSS rescoreEPSS 0.6% · 48th percentile
  69. 2026-09-04 05:07 UTCEPSS rescoreEPSS 0.6% · 48th percentile
  70. 2026-09-02 14:12 UTCEPSS rescoreEPSS 0.6% · 48th percentile
  71. 2026-09-01 13:54 UTCEPSS rescoreEPSS 0.6% · 48th percentile
  72. 2026-09-01 04:40 UTCEPSS rescoreEPSS 0.6% · 48th percentile
  73. 2026-08-31 00:09 UTCGHSA enrichmentGHSA-x5qg-qgv8-q7cr · GitHub severity HIGH · GitHub CVSS 9.1
  74. 2026-08-30 20:19 UTCEG score recompute
  75. 2026-08-30 20:19 UTCGHSA enrichmentGHSA-x5qg-qgv8-q7cr · GitHub severity HIGH · GitHub CVSS 9.1

Frequently asked(5)

What is CVE-2026-56111?
CVE-2026-56111 is a critical-severity vulnerability; its CVE record was published on June 24, 2026. Marlin Firmware through 2.1.2.7, fixed in commit 1f255d1, when built with MESHBEDLEVELING 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…
When was CVE-2026-56111 made public?
CVE-2026-56111 was made public on June 23, 2026: that is the date its CVE record's CNA, VulnCheck, gives for when the vulnerability was made public. The CVE record itself was published on June 24, 2026. EchelonGraph's copy of the record carries a last-modified date of October 25, 2026; the record at its source may have been updated since.
Is CVE-2026-56111 actively exploited?
CVE-2026-56111 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.6% probability of exploitation in the next 30 days (50th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-56111?
CVE-2026-56111 has a CVSS base score of 9.1 (a secondary CVSS source that NVD displays; NVD's own analysis pending).
How do I remediate CVE-2026-56111?
An upstream fix for CVE-2026-56111 has been merged but is not yet in a tagged release. Until it ships, restrict network exposure of the affected system or apply the vendor's mitigation, then update to the release that contains the fix. The vendor advisories EchelonGraph has for CVE-2026-56111 are linked in the Vendor Advisories panel on this page.

Dependency Blast Radius

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