CVE-2026-67277

Published Sep 5, 2026

Last updated 2 months ago

Tunneling protocol

Firmware

Overview

AI description

Automated description summarized from trusted sources.

CVE-2026-67277 is a vulnerability affecting the bandwidth-test service within MikroTik RouterOS. This flaw allows an unauthenticated client to establish a "related" btest connection before the primary session has completed its authentication process. An attacker can leverage this state to initiate an IPv4 UDP test. When the `random-data` parameter is set to `false`, the sender transmits an uninitialized tail from a kernel packet buffer, which can lead to the leakage of kernel memory. Additionally, an unchecked, inverted packet-size interval can cause an unsigned integer underflow and anomalously large fragmented output, potentially resulting in a remote denial-of-service (DoS) attack that restarts the RouterOS kernel or crashes the device.

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)
Source: cvd@cert.pl
NVD status: Analyzed
Products: routeros

Risk scores

CVSS 4.0

Type: Secondary
Base score: 8.8
Impact score: -
Exploitability score: -
Vector string: 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
Severity: HIGH

CVSS 3.1

Type: Primary
Base score: 8.2
Impact score: 4.2
Exploitability score: 3.9
Vector string: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:H
Severity: HIGH

Known exploits

Data from CISA

Vulnerability name: MikroTik RouterOS Missing Authentication for Critical Function Vulnerability
Exploit added on: Sep 10, 2026
Exploit action due: Sep 13, 2026
Required 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.

Weaknesses

cvd@cert.pl: CWE-306

Hype score: Not currently trending

Configurations

[
  {
    "nodes": [
      {
        "cpeMatch": [
          {
            "criteria": "cpe:2.3:o:mikrotik:routeros:*:*:*:*:*:*:*:*",
            "matchCriteriaId": "CFC981EC-B44C-40B5-945B-2283FADEC961",
            "versionEndExcluding": "6.49.21",
            "versionStartIncluding": "6.0",
            "vulnerable": true
          },
          {
            "criteria": "cpe:2.3:o:mikrotik:routeros:*:*:*:*:*:*:*:*",
            "matchCriteriaId": "881306AB-32B1-4B5F-96D8-9532D25F7AE4",
            "versionEndExcluding": "7.23.4",
            "versionStartIncluding": "7.0",
            "vulnerable": true
          },
          {
            "criteria": "cpe:2.3:o:mikrotik:routeros:*:*:*:*:*:*:*:*",
            "matchCriteriaId": "A41D6B3C-D321-4C61-B3D5-00F8276CB4AC",
            "versionEndExcluding": "7.24.2",
            "versionStartIncluding": "7.24",
            "vulnerable": true
          }
        ],
        "negate": false,
        "operator": "OR"
      }
    ]
  }
]

References

Sources include official advisories and independent security research.