CVE-2026-67277

CRITICALNVD 8.29.0▲
EchelonGraph scoreHIGH confidence

Score elevated to 9.0 because this CVE is listed on the CISA Known Exploited Vulnerabilities catalog (added 2026-09-10), indicating real-world exploitation has been confirmed by US federal agencies. NVD baseline CVSS 8.2 retained for reference. Confidence: HIGH.

Triggered by: CISA KEV (actively exploited)
Sources: cisa_kev, epss, ghsa, nvd
Trending — KEV-added this weekExploited in the wild
9.0EG
EchelonGraph verdictPatch nowTreat as an emergency — this is being exploited.
  • Actively exploited in the wild (CISA-KEV)
CISA-KEV: ExploitedEPSS PROB: 1%CVSS: 8.2Exploit: cisa kev · ssvc activeExposed: 0

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

RouterOS accepts a "related" btest connection before the corresponding primary session has completed authentication. An unauthenticated client can use this state to start an IPv4 UDP test. With "random-data=false", the sender transmits an uninitialized tail from a kernel packet buffer. A separate unchecked, inverted packet-size interval causes unsigned integer underflow, anomalously large fragmented output, and can restart the RouterOS kernel.

This issue was fixed in versions: 6.49.21 (Long-term), 7.23.4 (Long-term) and 7.24.2 (Stable)

CVSS v3
8.2
EG Score
9.0(high)
EG Risk
96(Attend)
EG Risk 96/100SSVC: Attend

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
Severity90% × 45%
Exploitation100% × 40%
Automatability100% × 15%
Action: Remediate soon — notable exploitation risk.
EPSS PROB
1%
EPSS %ILE
57%
KEV
⚠ Exploited

Published

September 5, 2026

Last Modified

September 11, 2026

Advisory Details (7)

Auto-updated Sep 5, 2026
⚠️ Active exploitation confirmed. Patch available.
generic

7.24.2 [stable] is released! - Announcements - MikroTik community forum

https://forum.mikrotik.com/t/7-24-2-stable-is-released/272800
generic

7.23.4 [long-term] is released! - Announcements - MikroTik community forum

https://forum.mikrotik.com/t/7-23-4-long-term-is-released/272801
generic

6.49.21 [long-term] is released! - Announcements - MikroTik community forum

https://forum.mikrotik.com/t/6-49-21-long-term-is-released/272802
generic

MikroTik · September 2026 vulnerability

https://mikrotik.com/supportsec/september-2026-vulnerability/
generic

Reversing MikroTik's Silent Patch: The RouterOS 7.23.4 Fix They Wouldn't Explain | Nick Pratley

https://npratley.net/reversing-mikrotiks-silent-patch-the-routeros-7-23-4-fix-they-wouldnt-explain/
generic🔴 Active Exploitation

Critical vulnerabilities in MikroTik RouterOS are being actively exploited. Immediate update recommended | CERT Polska

https://cert.pl/en/posts/2026/09/vulnerabilities-in-mikrotik-routeros-actively-exploited/
generic Patch Available

Vulnerabilities in Mikrotik RouterOS software | CERT Polska

https://cert.pl/en/posts/2026/09/mikrotik-routeros-cve

Vendor Advisories for CVE-2026-67277(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 56× in last 7d / 124× 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 124 total refreshes for this CVE.

  1. 2026-09-21 04:52 UTCGHSA enrichment
  2. 2026-09-21 00:46 UTCGHSA enrichment
  3. 2026-09-20 20:42 UTCEG score recompute
  4. 2026-09-20 20:42 UTCGHSA enrichment
  5. 2026-09-20 20:16 UTCEPSS rescore
  6. 2026-09-20 16:38 UTCGHSA enrichment
  7. 2026-09-20 12:34 UTCGHSA enrichment
  8. 2026-09-20 08:31 UTCGHSA enrichment
  9. 2026-09-20 04:27 UTCGHSA enrichment
  10. 2026-09-20 00:23 UTCGHSA enrichment
  11. 2026-09-19 20:20 UTCGHSA enrichment
  12. 2026-09-19 16:16 UTCEG score recompute
  13. 2026-09-19 16:16 UTCGHSA enrichment
  14. 2026-09-19 12:13 UTCGHSA enrichment
  15. 2026-09-19 08:10 UTCGHSA enrichment
  16. 2026-09-19 04:06 UTCGHSA enrichment
  17. 2026-09-19 00:03 UTCGHSA enrichment
  18. 2026-09-18 19:59 UTCEG score recompute
  19. 2026-09-18 19:59 UTCGHSA enrichment
  20. 2026-09-18 19:28 UTCEPSS rescore
  21. 2026-09-18 19:20 UTCCISA KEV update
  22. 2026-09-18 15:55 UTCGHSA enrichment
  23. 2026-09-18 14:15 UTCCISA KEV update
  24. 2026-09-18 11:48 UTCGHSA enrichment
  25. 2026-09-18 07:44 UTCGHSA enrichment
Show 75 more
  1. 2026-09-18 03:40 UTCGHSA enrichment
  2. 2026-09-17 23:36 UTCEG score recompute
  3. 2026-09-17 23:36 UTCGHSA enrichment
  4. 2026-09-17 19:31 UTCGHSA enrichment
  5. 2026-09-17 15:27 UTCGHSA enrichment
  6. 2026-09-17 11:23 UTCGHSA enrichment
  7. 2026-09-17 07:18 UTCGHSA enrichment
  8. 2026-09-17 03:15 UTCGHSA enrichment
  9. 2026-09-16 23:11 UTCGHSA enrichment
  10. 2026-09-16 19:07 UTCGHSA enrichment
  11. 2026-09-16 15:03 UTCEG score recompute
  12. 2026-09-16 15:03 UTCGHSA enrichment
  13. 2026-09-16 14:10 UTCCISA KEV update
  14. 2026-09-16 14:08 UTCEPSS rescore
  15. 2026-09-16 10:59 UTCGHSA enrichment
  16. 2026-09-16 06:55 UTCEG score recompute
  17. 2026-09-16 06:55 UTCGHSA enrichment
  18. 2026-09-16 05:15 UTCEPSS rescore
  19. 2026-09-16 02:52 UTCGHSA enrichment
  20. 2026-09-15 22:48 UTCGHSA enrichment
  21. 2026-09-15 18:44 UTCGHSA enrichment
  22. 2026-09-15 14:40 UTCGHSA enrichment
  23. 2026-09-15 10:36 UTCGHSA enrichment
  24. 2026-09-15 06:32 UTCEG score recompute
  25. 2026-09-15 06:32 UTCGHSA enrichment
  26. 2026-09-15 02:28 UTCGHSA enrichment
  27. 2026-09-14 22:24 UTCGHSA enrichment
  28. 2026-09-14 19:24 UTCCISA KEV update
  29. 2026-09-14 18:18 UTCGHSA enrichment
  30. 2026-09-14 14:15 UTCGHSA enrichment
  31. 2026-09-14 10:11 UTCGHSA enrichment
  32. 2026-09-14 06:08 UTCGHSA enrichment
  33. 2026-09-14 02:04 UTCGHSA enrichment
  34. 2026-09-13 22:00 UTCGHSA enrichment
  35. 2026-09-13 17:56 UTCEG score recompute
  36. 2026-09-13 17:56 UTCGHSA enrichment
  37. 2026-09-13 13:52 UTCGHSA enrichment
  38. 2026-09-13 09:48 UTCGHSA enrichment
  39. 2026-09-13 05:45 UTCGHSA enrichment
  40. 2026-09-13 01:41 UTCGHSA enrichment
  41. 2026-09-12 21:37 UTCGHSA enrichment
  42. 2026-09-12 17:34 UTCEG score recompute
  43. 2026-09-12 17:34 UTCGHSA enrichment
  44. 2026-09-12 13:28 UTCGHSA enrichment
  45. 2026-09-12 09:24 UTCGHSA enrichment
  46. 2026-09-12 05:19 UTCGHSA enrichment
  47. 2026-09-12 01:15 UTCGHSA enrichment
  48. 2026-09-11 21:11 UTCGHSA enrichment
  49. 2026-09-11 18:49 UTCCISA KEV update
  50. 2026-09-11 17:07 UTCEG score recompute
  51. 2026-09-11 17:07 UTCGHSA enrichment
  52. 2026-09-11 14:53 UTCEPSS rescore
  53. 2026-09-11 13:03 UTCEG score recompute
  54. 2026-09-11 13:03 UTCGHSA enrichment
  55. 2026-09-11 13:02 UTCNVD updateCVSS v3 → 8.2
  56. 2026-09-11 12:28 UTCEG score recompute
  57. 2026-09-11 12:28 UTCGHSA enrichment
  58. 2026-09-11 09:37 UTCEPSS rescore
  59. 2026-09-11 08:24 UTCGHSA enrichment
  60. 2026-09-11 04:20 UTCEG score recompute
  61. 2026-09-11 04:20 UTCGHSA enrichment
  62. 2026-09-11 04:00 UTCEG score recompute
  63. 2026-09-11 04:00 UTCGHSA enrichment
  64. 2026-09-11 00:22 UTCEG score recompute
  65. 2026-09-11 00:22 UTCGHSA enrichment
  66. 2026-09-10 20:18 UTCEG score recompute
  67. 2026-09-10 20:18 UTCGHSA enrichment
  68. 2026-09-10 20:10 UTCGHSA enrichment
  69. 2026-09-10 19:55 UTCEG score recompute
  70. 2026-09-10 19:55 UTCGHSA enrichment
  71. 2026-09-10 19:29 UTCEG score recompute▲ 0.20
  72. 2026-09-10 19:29 UTCGHSA enrichment
  73. 2026-09-10 19:28 UTCCISA KEV update
  74. 2026-09-10 07:03 UTCGHSA enrichment
  75. 2026-09-09 18:17 UTCGHSA enrichment

Related CVEs(same CWE)

Frequently asked(6)

What is CVE-2026-67277?
CVE-2026-67277 is a critical vulnerability published on September 5, 2026. RouterOS accepts a "related" btest connection before the corresponding primary session has completed authentication. An unauthenticated client can use this state to start an IPv4 UDP test. With "random-data=false", the sender transmits an uninitialized tail from a kernel packet buffer. A separate…
When was CVE-2026-67277 disclosed?
CVE-2026-67277 was first published in the National Vulnerability Database on September 5, 2026, with the most recent update on September 11, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-67277 actively exploited?
Yes. CISA added CVE-2026-67277 to the Known Exploited Vulnerabilities catalog on September 10, 2026, affecting MikroTik RouterOS. KEV listing indicates confirmed exploitation in the wild; this CVE warrants immediate patching attention.
What is the CVSS score of CVE-2026-67277?
CVE-2026-67277 has a CVSS v3 base score of 8.2 (NVD). EchelonGraph synthesises NVD + CISA KEV + FIRST EPSS + GHSA into a combined EG score of 9.0.
Which products are affected by CVE-2026-67277?
CVE-2026-67277 affects MikroTik RouterOS. The full affected-products list, including version ranges and fixed versions, is shown in the Affected Packages section of this page.
How do I remediate CVE-2026-67277?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-67277, 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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