Vulnerability in Mikrotik Routeros
CVE-2026-67278
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.
Published · last modified .
CVSS v3 metric
CVSS v3 base score 9.1 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N.
EPSS exploit prediction
EPSS: 0.003 (15.7th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 16th percentile — 15.7% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.002 · newest: 0.003 · change: +0.001
Affected products
Weakness classification (CWE)
References
- cert.pl/en/posts/2026/09/mikrotik-routeros-cve (Third Party Advisory, third-party-advisory)
- cert.pl/en/posts/2026/09/vulnerabilities-in-mikrotik-routeros-actively-exploite… (technical-description, Third Party Advisory, Mitigation)
- forum.mikrotik.com/t/6-49-21-long-term-is-released/272802 (release-notes)
- forum.mikrotik.com/t/7-23-4-long-term-is-released/272801 (release-notes)
- forum.mikrotik.com/t/7-24-2-stable-is-released/272800 (release-notes)
- mikrotik.com/supportsec/september-2026-vulnerability/ (vendor-advisory, Vendor Advisory)
- npratley.net/reversing-mikrotiks-silent-patch-the-routeros-7-23-4-fix-they-woul… (Exploit, Third Party Advisory, exploit)
- forum.mikrotik.com/t/7-23-6-long-term-is-released/273139 (release-notes, Release Notes)
- forum.mikrotik.com/t/7-24-3-stable-is-released/273138 (release-notes, Release Notes)
Frequently asked questions
- What is CVE-2026-67278?
- CVE-2026-67278 is a critical-severity vulnerability in Mikrotik Routeros, classified under Improper Verification of Cryptographic Signature. CVSS score: 9.1/10. Published 2026-09-05.
- How severe is CVE-2026-67278?
- Critical severity. CVSS v3 base score is 9.1 out of 10.