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MikroTik RouterOS Missing Authentication for Critical Function (CVE-2026-67277)

high Tenable OT Security Plugin ID 506059

Synopsis

The remote OT asset is affected by a vulnerability.

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)

This plugin only works with Tenable.ot.
Please visit https://www.tenable.com/products/tenable-ot for more information.

Solution

Refer to the vendor advisory.

See Also

https://cert.pl/en/posts/2026/09/mikrotik-routeros-cve

https://forum.mikrotik.com/t/6-49-21-long-term-is-released/272802

https://forum.mikrotik.com/t/7-23-4-long-term-is-released/272801

https://forum.mikrotik.com/t/7-24-2-stable-is-released/272800

https://mikrotik.com/supportsec/september-2026-vulnerability/

http://www.nessus.org/u?1fe530bb

http://www.nessus.org/u?eed3942f

http://www.nessus.org/u?f20c470c

Plugin Details

Severity: High

ID: 506059

File Name: tenable_ot_mikrotik_CVE-2026-67277.nasl

Version: 1.3

Type: Remote

Family: Tenable.ot

Published: 10/5/2026

Updated: 10/6/2026

Supported Sensors: Tenable OT Security

Risk Information

VPR

Risk Factor: Medium

Score: 6.5

Percentile: 96.46

CVSS v2

Risk Factor: High

Base Score: 8.5

Temporal Score: 7

Vector: CVSS2#AV:N/AC:L/Au:N/C:P/I:N/A:C

CVSS Score Source: CVE-2026-67277

CVSS v3

Risk Factor: High

Base Score: 8.2

Temporal Score: 7.6

Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:H

Temporal Vector: CVSS:3.0/E:F/RL:O/RC:C

CVSS v4

Risk Factor: High

Base Score: 8.8

Threat Score: 8.8

Threat Vector: CVSS:4.0/E:A

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

Vulnerability Information

CPE: cpe:/o:mikrotik:routeros:6, cpe:/o:mikrotik:routeros:7

Required KB Items: Tenable.ot/MikroTik

Exploit Available: true

Exploit Ease: Exploits are available

Patch Publication Date: 9/5/2026

Vulnerability Publication Date: 9/5/2026

CISA Known Exploited Vulnerability Due Dates: 9/13/2026

Reference Information

CVE: CVE-2026-67277

CWE: 306