{
  "id": "CVE-2026-67277",
  "url": "https://spydr.io/cve/CVE-2026-67277",
  "published": "2026-09-05T20:17:18.120Z",
  "modified": "2026-09-11T12:52:29.533Z",
  "score": 8.8,
  "severity": "high",
  "cvss_version": "4.0",
  "vector": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X",
  "score_source": "cert.pl",
  "epss": 0.0156,
  "epss_percentile": 0.74384,
  "exploited": true,
  "kev": {
    "added": "2026-09-10",
    "due": "2026-09-13",
    "action": "Apply mitigations in accordance with vendor instructions, ensuring compliance with CISA’s BOD 26-04 Prioritizing Security Updates Based on Risk (see URL in Notes) guidance and CISA’s “Forensics Triage Requirements” (see URL in Notes). Follow applicable BOD 26-04 guidance for cloud services or discontinue use of the product if mitigations are unavailable. Stakeholders are responsible for evaluating each asset's internet exposure and ensuring adherence to BOD 26-04 patching guidelines.",
    "ransomware": "Unknown",
    "name": "MikroTik RouterOS Missing Authentication for Critical Function Vulnerability",
    "notes": "https://mikrotik.com/supportsec/september-2026-vulnerability/ ; BOD 26-04: https://www.cisa.gov/news-events/directives/bod-26-04-prioritizing-security-updates-based-risk ; Forensics Triage Requirements: https://www.cisa.gov/news-events/directives/bod-26-04-implementation-guidance-prioritizing-security-updates-based-risk ; https://nvd.nist.gov/vuln/detail/CVE-2026-67277"
  },
  "ssvc_exploitation": "active",
  "vendors": [
    "Mikrotik"
  ],
  "products": [
    "Mikrotik RouterOS"
  ],
  "cwes": [
    "CWE-306"
  ],
  "description": "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)",
  "status": "Analyzed",
  "score_type": "Secondary",
  "scores": {
    "cvss_v40": 8.8,
    "cvss_v31": 8.2,
    "cvss_v30": null
  },
  "references": [
    {
      "url": "https://cert.pl/en/posts/2026/09/mikrotik-routeros-cve",
      "tags": [
        "Third Party Advisory"
      ]
    },
    {
      "url": "https://cert.pl/en/posts/2026/09/vulnerabilities-in-mikrotik-routeros-actively-exploited/",
      "tags": [
        "Mitigation",
        "Third Party Advisory"
      ]
    },
    {
      "url": "https://forum.mikrotik.com/t/6-49-21-long-term-is-released/272802",
      "tags": [
        "Release Notes"
      ]
    },
    {
      "url": "https://forum.mikrotik.com/t/7-23-4-long-term-is-released/272801",
      "tags": [
        "Release Notes"
      ]
    },
    {
      "url": "https://forum.mikrotik.com/t/7-24-2-stable-is-released/272800",
      "tags": [
        "Release Notes"
      ]
    },
    {
      "url": "https://mikrotik.com/supportsec/september-2026-vulnerability/",
      "tags": [
        "Vendor Advisory"
      ]
    },
    {
      "url": "https://npratley.net/reversing-mikrotiks-silent-patch-the-routeros-7-23-4-fix-they-wouldnt-explain/",
      "tags": [
        "Exploit",
        "Third Party Advisory"
      ]
    },
    {
      "url": "https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-67277",
      "tags": [
        "US Government Resource"
      ]
    }
  ],
  "nvd_url": "https://nvd.nist.gov/vuln/detail/CVE-2026-67277",
  "covered_in": [],
  "attribution": [
    {
      "source": "NVD",
      "url": "https://nvd.nist.gov",
      "notice": "This product uses data from the NVD API but is not endorsed or certified by the NVD."
    },
    {
      "source": "CISA KEV",
      "url": "https://www.cisa.gov/known-exploited-vulnerabilities-catalog",
      "notice": "Known exploited vulnerabilities from the CISA KEV catalog."
    },
    {
      "source": "FIRST EPSS",
      "url": "https://www.first.org/epss",
      "notice": "Exploit prediction scores from FIRST EPSS."
    }
  ]
}