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CVE-2026-67278

Mikrotik Routeros vulnerability

9.1 CRITICALPublic exploitEPSS 0.25%
  1. Published5 Sept 2026

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.

CVSS 3.1 breakdown

Attack vectorNetwork
Attack complexityLow
Privileges requiredNone
User interactionNone
ScopeUnchanged
ConfidentialityHigh
IntegrityHigh
AvailabilityNone
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

Affected products

Mikrotik Routeros≥ 7.0 < 7.23.6 · ≥ 7.24 < 7.24.3

Remediation

Fixed in
Mikrotik Routeros≥ 7.23.6

References

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Frequently asked

Is CVE-2026-67278 being actively exploited?

CVE-2026-67278 is not in the CISA KEV catalog. A public exploit reference exists, so treat it as exploitable. Its EPSS exploit probability is 0.25%.

How severe is CVE-2026-67278?

CVE-2026-67278 has a CVSS 3.1 base score of 9.1, rated critical. EPSS estimates a 0.25% probability of exploitation.

Which products are affected by CVE-2026-67278?

Affected products include Mikrotik Routeros.

How do I fix CVE-2026-67278?

Upgrade affected software to a fixed version, for example Mikrotik Routeros 7.23.6 or later, then confirm no affected versions remain in your inventory.

How Secuno handles this

Secuno correlates vulnerabilities like CVE-2026-67278 against the real software inventory on every managed device, as each hourly inventory arrives. Rather than a static severity, each match is scored in context: exploit availability, EPSS, the asset's exposure, and business criticality decide where it lands in the queue. If an affected version is present anywhere across your portfolio, it surfaces automatically with a prioritised remediation path.

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Data from the NVD, CISA KEV catalog and FIRST EPSS. CVSS 3.1 base score shown where available.