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CVE-2026-67278

9.1 · CRITICAL

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.

Published Sep 5, 2026mikrotikCWE-347EPSS 0.26%

Overview

CVE-2026-67278 is a critical-severity vulnerability affecting mikrotik routeros. It was published on September 5, 2026 and has a CVSS 3.1 base score of 9.1 (CRITICAL).

This vulnerability has a CVSS 3.1 base score of 9.1, rated CRITICAL. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.

Technical description

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.

Remediation

Check the references section for vendor advisories and patches from mikrotik. Update routeros to the latest patched version. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

Affected products

VendorProductVersionsStatus
mikrotikrouteros>= 7.0, < 7.23.6Affected

References

Refcert.pl/en/posts/2026/09/mikrotik-routeros-cveRefcert.pl/en/posts/2026/09/vulnerabilities-in-mikrotik-routeros-actively-exploited/Refforum.mikrotik.com/t/7-23-6-long-term-is-released/273139Refforum.mikrotik.com/t/7-24-3-stable-is-released/273138Refmikrotik.com/supportsec/september-2026-vulnerability/Refnpratley.net/reversing-mikrotiks-silent-patch-the-routeros-7-23-4-fix-they-wouldnt-explain/

How CyberStrike helps

Frequently asked questions

What is CVE-2026-67278?

CVE-2026-67278 is a critical-severity vulnerability affecting mikrotik routeros. It was published on September 5, 2026 and has a CVSS 3.1 base score of 9.1 (CRITICAL).

How severe is CVE-2026-67278?

This vulnerability has a CVSS 3.1 base score of 9.1, rated CRITICAL. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.

How do I fix or remediate CVE-2026-67278?

Check the references section for vendor advisories and patches from mikrotik. Update routeros to the latest patched version. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

How can CyberStrike help with CVE-2026-67278?

CyberStrike is an open-source, AI-augmented pentesting engine. Rather than flag a version number, it tests whether an issue like CVE-2026-67278 is actually reachable in your own applications and APIs, then verifies each finding before reporting it. That tells you if the weakness is a real, exploitable risk in your environment or a false positive you can safely deprioritize.

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