---
id: CVE-2026-67278
title: >-
  MikroTik RouterOS accepts malformed RSA/PKCS#1 v1.5 signatures across
  RSA-based services, including TLS/X.509 certificate validation and SSH
  host-key authentication
summary: >-
  MikroTik RouterOS accepts malformed RSA/PKCS#1 v1.5 signatures across
  RSA-based services, including TLS/X.509 certificate validation and SSH
  host-key authentication. Because its trust store includes an e=3 root CA, an
  attacker controllin…
severity: critical
cvss: 9.1
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N'
cwe:
  - CWE-347
vendor: mikrotik
product: routeros
affected:
  - 'routeros >= 7.0, < 7.23.6'
  - 'routeros >= 7.24, < 7.24.3'
patched:
  - routeros 7.24.3
published: '2026-09-05'
updated: '2026-09-25'
sourceUpdated: '2026-09-25T14:56:04.743'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-67278'
references:
  - url: 'https://cert.pl/en/posts/2026/09/mikrotik-routeros-cve'
    label: cvd@cert.pl
  - url: >-
      https://cert.pl/en/posts/2026/09/vulnerabilities-in-mikrotik-routeros-actively-exploited/
    label: cvd@cert.pl
  - url: 'https://forum.mikrotik.com/t/7-23-6-long-term-is-released/273139'
    label: cvd@cert.pl
  - url: 'https://forum.mikrotik.com/t/7-24-3-stable-is-released/273138'
    label: cvd@cert.pl
  - url: 'https://mikrotik.com/supportsec/september-2026-vulnerability/'
    label: cvd@cert.pl
  - url: >-
      https://npratley.net/reversing-mikrotiks-silent-patch-the-routeros-7-23-4-fix-they-wouldnt-explain/
    label: cvd@cert.pl
  - url: 'https://forum.mikrotik.com/t/7-23-4-long-term-is-released/272801'
    label: cvd@cert.pl
  - url: 'https://forum.mikrotik.com/t/7-24-2-stable-is-released/272800'
    label: cvd@cert.pl
  - url: 'https://forum.mikrotik.com/t/6-49-21-long-term-is-released/272802'
    label: cvd@cert.pl
tags:
  - nvd
  - cve.org
  - exploit-available
  - score-dispute
epss: 0.00278
epssPercentile: 0.18064
exploitAvailable: true
ssvc:
  exploitation: poc
  automatable: 'no'
  technicalImpact: partial
  timestamp: '2026-09-08T15:30:45.430794Z'
scores:
  nvd: 9.1
  cna: 6.3
ingestedAt: '2026-09-06T10:53:52.423Z'
---

## Overview

MikroTik RouterOS accepts malformed RSA/PKCS#1 v1.5 signatures across RSA-based services, including TLS/X.509 certificate validation and SSH host-key authentication. 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. The same permissive verification also undermines RSA-based SSH authentication.



This issue affects only 7.x branch was fixed in versions: 7.23.6 (Long-term) and 7.24.3 (Stable).
Releases 7.23.4 and 7.24.2 included an incomplete fix.

## Affected

- `routeros >= 7.0, < 7.23.6`
- `routeros >= 7.24, < 7.24.3`

## Remediation

Upgrade past the affected range:

- `routeros 7.24.3`