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)

Metrics

Attack Vector Network

Attack Complexity Low

Privileges Required None

Attack Requirements None

User Interaction None

Vulnerable System Confidentiality Impact Low

Vulnerable System Integrity Impact None

Vulnerable System Availability Impact High

Subsequent System Confidentiality Impact None

Subsequent System Integrity Impact None

Subsequent System Availability Impact None

No CVSS v3.1

No CVSS v3.0

No CVSS v2

This CVE is not in the KEV list.

No EPSS score available.

Key SSVC decision points have not yet been added.

Affected Vendors & Products

Vendors Products
Mikrotik Subscribe
Routeros Subscribe

No data.

No data.

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Advisories

No advisories yet.

Fixes

Solution

No solution given by the vendor.

Workaround

No workaround given by the vendor.

References
Link Providers
https://cert.pl/en/posts/2026/09/mikrotik-routeros-cve cve-icon cve-icon
https://cert.pl/en/posts/2026/09/vulnerabilities-in-mikrotik-routeros-actively-exploited/ cve-icon cve-icon
https://forum.mikrotik.com/t/6-49-21-long-term-is-released/272802 cve-icon cve-icon
https://forum.mikrotik.com/t/7-23-4-long-term-is-released/272801 cve-icon cve-icon
https://forum.mikrotik.com/t/7-24-2-stable-is-released/272800 cve-icon cve-icon
https://mikrotik.com/supportsec/september-2026-vulnerability/ cve-icon cve-icon
https://npratley.net/reversing-mikrotiks-silent-patch-the-routeros-7-23-4-fix-they-wouldnt-explain/ cve-icon cve-icon
History

Sat, 05 Sep 2026 20:45:00 +0000

Type Values Removed Values Added
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 (Lont-term), 7.23.4 (Lont-term) and 7.24.2 (Stable) 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)

Sat, 05 Sep 2026 20:15:00 +0000

Type Values Removed Values Added
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 (Lont-term), 7.23.4 (Lont-term) and 7.24.2 (Stable)
Title Kernel memory disclosure and denial of service in MikroTik RouterOS btest service
First Time appeared Mikrotik
Mikrotik routeros
Weaknesses CWE-306
CPEs cpe:2.3:a:mikrotik:routeros:*:*:*:*:*:*:*:*
Vendors & Products Mikrotik
Mikrotik routeros
References
Metrics cvssV4_0

{'score': 8.8, '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'}

Projects

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cve-icon MITRE

Status: PUBLISHED

Assigner: CERT-PL

Published:

Updated: 2026-09-05T20:39:44.166Z

Reserved: 2026-07-29T11:59:30.538Z

Link: CVE-2026-67277

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Received

Published: 2026-09-05T20:17:18.120

Modified: 2026-09-05T21:16:50.393

Link: CVE-2026-67277

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-09-05T21:30:17Z

Weaknesses