Name: CVE-2026-67277: Missing Authentication for Critical Function
Creator: Rapid7
Published: 2026-09-05T00:00:00.000Z
License: https://www.rapid7.com/legal/website-terms-of-use/
Keywords: CVE, CVE-2026-67277, CWE-306, Exploited in the Wild, CISA KEV Exploit, CVSS 8.2, EPSS 0.00435, CISA KEV

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 Details

CVSS 4.0 Base Score: 8.8 (HIGH)
CVSS 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)
CVSS 3.1 Base Score: 8.2
CVSS 3.1 Vector: (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:H)

Covered by Rapid7

Product	Vendor Advisory	Solution File	Added	Published
Mikrotik Routeros	—	Upgrade to latest version of MikroTik RouterOS	Oct 5, 2026	Sep 5, 2026

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CVSS Details

Covered by Rapid7

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