CVE-2026-71263

CRITICALPre-NVD 9.19.1—
EchelonGraph scoreHIGH confidence

Score 9.1 from GitHub Security Advisory (severity: CRITICAL) published 2026-08-05. a secondary CVSS source baseline 9.1; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, secondary
Trending — 3 sources updated this week
9.1EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 9.1Exploit: None knownExposed: 0

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

The LINUXTCP port of FreeModbus contains an off-by-one bounds check in xMBPortTCPPool (demo/LINUXTCP/port/porttcp.c). The check uses a strict greater-than comparison instead of greater-than-or-equal against the 263-byte MB_TCP_BUF_SIZE limit.

CVSS v3
9.1
EG Score
9.1(high)
EG Risk
56(Track)
EG Risk 56/100SSVC: 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
Severity91% × 45%
Exploitation0% × 40%
Automatability100% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
20%
KEV
Not listed

Published

August 5, 2026

Last Modified

August 10, 2026

Advisory Details (2)

Auto-updated Aug 5, 2026
No patch confirmed yet.
generic

freemodbus/demo/LINUXTCP/port/porttcp.c at master · cwalter-at/freemodbus · GitHub

https://github.com/cwalter-at/freemodbus/blob/master/demo/LINUXTCP/port/porttcp.c
generic

GitHub - cwalter-at/freemodbus: BSD licensed MODBUS RTU/ASCII and TCP slave · GitHub

https://github.com/cwalter-at/freemodbus

Vendor Advisories for CVE-2026-71263(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 / 137× 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 137 total refreshes for this CVE.

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

Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2026-71263?
CVE-2026-71263 is a critical vulnerability published on August 5, 2026. The LINUXTCP port of FreeModbus contains an off-by-one bounds check in xMBPortTCPPool (demo/LINUXTCP/port/porttcp.c). The check uses a strict greater-than comparison instead of greater-than-or-equal against the 263-byte MBTCPBUF_SIZE limit.
When was CVE-2026-71263 disclosed?
CVE-2026-71263 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-2026-71263 actively exploited?
CVE-2026-71263 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 79.6% of all scored CVEs.
What is the CVSS score of CVE-2026-71263?
CVE-2026-71263 has a CVSS v3 base score of 9.1 (NVD).
How do I remediate CVE-2026-71263?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-71263, 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.

Dependency Blast Radius

Explore the affected products and dependency analysis for CVE-2026-71263

Explore →

Is Your Infrastructure Affected by CVE-2026-71263?

EchelonGraph automatically scans your cloud infrastructure and maps CVE exposure using blast radius analysis.

Start Free Scan →Browse All CVEs