CVE-2026-67277

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 HIGH

8.2^/10

CVSS v3 : HIGH

Vector :

Exploitability : 3.9 / Impact : 4.2

Attack Vector NETWORK

Attack Complexity LOW

Privileges Required NONE

User Interaction NONE

Confidentiality Impact LOW

Integrity Impact NONE

Availability Impact HIGH

Scope UNCHANGED

References

Link	Resource
https://cert.pl/en/posts/2026/09/mikrotik-routeros-cve	Third Party Advisory
https://cert.pl/en/posts/2026/09/vulnerabilities-in-mikrotik-routeros-actively-exploited/	Mitigation Third Party Advisory
https://forum.mikrotik.com/t/6-49-21-long-term-is-released/272802	Release Notes
https://forum.mikrotik.com/t/7-23-4-long-term-is-released/272801	Release Notes
https://forum.mikrotik.com/t/7-24-2-stable-is-released/272800	Release Notes
https://mikrotik.com/supportsec/september-2026-vulnerability/	Vendor Advisory
https://npratley.net/reversing-mikrotiks-silent-patch-the-routeros-7-23-4-fix-they-wouldnt-explain/	Exploit Third Party Advisory
https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-67277	US Government Resource

Configurations

Configuration 1 (hide)

OR	cpe:2.3:o:mikrotik:routeros::::::::
	cpe:2.3:o:mikrotik:routeros::::::::
	cpe:2.3:o:mikrotik:routeros::::::::

History

No history.

Information

Published : 2026-09-05 20:17

Updated : 2026-09-11 12:52

NVD link : CVE-2026-67277

Mitre link : CVE-2026-67277

CVE.ORG link : CVE-2026-67277

JSON object : View

Products Affected

mikrotik

routeros

CWE

CWE-306

Missing Authentication for Critical Function

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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.\n\n\n\nThis issue was fixed in versions:\u00a06.49.21 (Long-term),\u00a07.23.4 (Long-term)\u00a0and\u00a07.24.2 (Stable)"}], "lastModified": "2026-09-11T12:52:29.533", "cisaActionDue": "2026-09-13", "cisaExploitAdd": "2026-09-10", "configurations": [{"nodes": [{"negate": false, "cpeMatch": [{"criteria": "cpe:2.3:o:mikrotik:routeros:*:*:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "CFC981EC-B44C-40B5-945B-2283FADEC961", "versionEndExcluding": "6.49.21", "versionStartIncluding": "6.0"}, {"criteria": "cpe:2.3:o:mikrotik:routeros:*:*:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "881306AB-32B1-4B5F-96D8-9532D25F7AE4", "versionEndExcluding": "7.23.4", "versionStartIncluding": "7.0"}, {"criteria": "cpe:2.3:o:mikrotik:routeros:*:*:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "A41D6B3C-D321-4C61-B3D5-00F8276CB4AC", "versionEndExcluding": "7.24.2", "versionStartIncluding": "7.24"}], "operator": "OR"}]}], "sourceIdentifier": "cvd@cert.pl", "cisaRequiredAction": "Apply mitigations in accordance with vendor instructions, ensuring compliance with CISA\u2019s BOD 26-04 Prioritizing Security Updates Based on Risk (see URL in Notes) guidance and CISA\u2019s \u201cForensics Triage Requirements\u201d (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.", "cisaVulnerabilityName": "MikroTik RouterOS Missing Authentication for Critical Function Vulnerability"}