MikroTik RouterOS 7.0.x < 7.23.4 / 7.24.x < 7.24.2 X.509 Signature Validation Bypass (CVE-2026-67278)

critical Nessus Plugin ID 344587

Synopsis

The remote networking device is affected by a certificate validation vulnerability.

Description

According to its self-reported version, the remote networking device is running a version of MikroTik RouterOS 7.0.x prior to 7.23.4, or 7.24.x prior to 7.24.2. It is, therefore, affected by a certificate validation vulnerability.

MikroTik RouterOS accepts malformed RSA/PKCS#1 v1.5 signatures during X.509 validation. Because its trust store includes an e=3 root CA, an attacker controlling or redirecting an outbound RouterOS TLS connection can use the root's public certificate - without its private key - to forge a trusted intermediate and issue certificates for arbitrary hostnames, enabling TLS server impersonation. (CVE-2026-67278)

Note that Nessus has not tested for this issue but has instead relied only on the router's self-reported version number.

Solution

Upgrade to MikroTik RouterOS 7.23.4, 7.24.2 or later.

Plugin Details

Severity: Critical

ID: 344587

File Name: mikrotik_CVE-2026-67278.nasl

Version: 1.1

Type: Remote

Family: Misc.

Published: 9/10/2026

Updated: 9/10/2026

Configuration: Enable thorough checks (optional)

Supported Sensors: Nessus

Risk Information

VPR

Risk Factor: Medium

Score: 4.3

Percentile: 53.47

CVSS v2

Risk Factor: Medium

Base Score: 5

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

CVSS Score Source: CVE-2026-67278

CVSS v3

Risk Factor: Critical

Base Score: 9.1

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

Vulnerability Information

CPE: cpe:/o:mikrotik:routeros

Required KB Items: MikroTik/RouterOS/Version

Patch Publication Date: 9/3/2026

Vulnerability Publication Date: 9/5/2026

Reference Information

CVE: CVE-2026-67278

Detections

Analytics