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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…

NVD (opens in a new tab) CVE.org (opens in a new tab)
CVSS
9.1, critical critical CVSS v3.1
EPSS, next 30 days
0.3% higher than 15.5% of scored CVEs
Exploitation
Exploit code published
Published
5 Sept 2026a month ago

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.

Details

Vendor
Mikrotik
Product
RouterOS
Weakness
CWE-347 (opens in a new tab)
Status
Analyzed
Updated
25 Sept 2026
Assigner
cvd@cert.pl

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

References 6

Exploit code 1

Advisories 3

Other references 2

The kind is read from NVD's tags where present and from the shape of the URL otherwise, so treat it as a hint.

Other Mikrotik CVEs

Every Mikrotik CVE we hold

Same vendor in what we hold, not a known link between the flaws.

  • CVE-2026-67277 MikroTik RouterOS Missing Authentication for Critical Function Vulnerability KEV EPSS 2% 8.2, high
  • CVE-2026-67279 Mikrotik RouterOS Improper Enforcement of Behavioral Workflow Vulnerability KEV EPSS 1% 6.5, medium
  • CVE-2026-86060 MikroTik RouterOS Improper Neutralization of Argument Delimiters in a Command Vulnerability KEV EPSS 6% 9.8, critical
  • CVE-2018-14847 MikroTik Router OS Directory Traversal Vulnerability KEV EPSS 96% 9.1, critical
  • CVE-2018-7445 MikroTik RouterOS Stack-Based Buffer Overflow Vulnerability KEV EPSS 61% 9.8, critical
  • CVE-2026-67276 RouterOS does not compare the complete RSA public key when matching an SSH authentication request to an authorized user key, checking… EPSS 6% 8.1, high
  • CVE-2026-67281 Mikrotik RouterOS Path Traversal Vulnerability EPSS 0.7% 7.5, high

Beyond this page

Is CVE-2026-67278 in your network?

This page tells you how dangerous CVE-2026-67278 is out there. Whether it sits on one of your devices, only a scan of your own network can tell. That is what our systems do, every day, for the companies we protect.

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Check your exposure

Assembled from the NVD 2.0 API, the CISA Known Exploited Vulnerabilities Catalog and FIRST EPSS. Scores are as of our last collection on 17 Oct 2026, not the live upstream state.