CVE-2026-71256

CRITICALPre-NVD 9.89.8—
EchelonGraph scoreHIGH confidence

Score 9.8 from GitHub Security Advisory (severity: CRITICAL) published 2026-08-05. a secondary CVSS source baseline 9.8; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, secondary
Trending — 3 sources updated this week
9.8EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 9.8Exploit: None knownExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

nanoMODBUS through v1.23.0 contains an out-of-bounds stack read leading to a wild-pointer write in nmbs_read_device_identification_basic / recv_read_device_identification_res in nanomodbus.c. A fixed 3-element stack array order[3] = {0,1,2} maps object IDs to buffer indices. The server-supplied object_id field (0-255, read directly from the wire) is used without any bounds check as buf_index = order[object_id].

CVSS v3
9.8
EG Score
9.8(high)
EG Risk
59(Track)
EG Risk 59/100SSVC: Track

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity98% × 45%
Exploitation0% × 40%
Automatability100% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
24%
KEV
Not listed

Published

August 5, 2026

Last Modified

August 10, 2026

Advisory Details (2)

Auto-updated Aug 17, 2026
No patch confirmed yet.
generic

nanoMODBUS/nanomodbus.c at master · debevv/nanoMODBUS · GitHub

https://github.com/debevv/nanoMODBUS/blob/master/nanomodbus.c
generic

GitHub - debevv/nanoMODBUS: A compact MODBUS RTU/TCP C library for embedded/microcontrollers · GitHub

https://github.com/debevv/nanoMODBUS

Vendor Advisories for CVE-2026-71256(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 60× in last 7d / 142× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. 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. Most recent first.

Showing the most recent 100 of 142 total refreshes for this CVE.

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

Frequently asked(5)

What is CVE-2026-71256?
CVE-2026-71256 is a critical vulnerability published on August 5, 2026. nanoMODBUS through v1.23.0 contains an out-of-bounds stack read leading to a wild-pointer write in nmbsreaddeviceidentificationbasic / recvreaddeviceidentificationres in nanomodbus.c. A fixed 3-element stack array order[3] = {0,1,2} maps object IDs to buffer indices. The server-supplied objectid…
When was CVE-2026-71256 disclosed?
CVE-2026-71256 was first published in the National Vulnerability Database on August 5, 2026, with the most recent update on August 10, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-71256 actively exploited?
CVE-2026-71256 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0% probability of exploitation in the next 30 days, which ranks it in the top 76.5% of all scored CVEs.
What is the CVSS score of CVE-2026-71256?
CVE-2026-71256 has a CVSS v3 base score of 9.8 (NVD).
How do I remediate CVE-2026-71256?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-71256, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

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