CVE-2026-67277

HIGH

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 v3.1 Score

8.2
HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:H
Attack Vector
NETWORK
Complexity
LOW
Privileges
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
LOW
Integrity
NONE
Availability
HIGH
Published: 9/5/2026Modified: 9/11/2026

Related Intelligence (0)

No articles currently reference this CVE.

References (8)

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