CVE-2026-67278: TLS server impersonation possible in Mikrotik RouterOS

Q: Which RouterOS connections are exposed to this attack?

Outbound TLS connections are exposed when an attacker can control or redirect the RouterOS device's connection to the intended server.

Q: Does an attacker need the trusted root CA's private key?

No. The attacker can use the root CA's public certificate to forge a trusted intermediate certificate and issue certificates for arbitrary hostnames.

Q: Which versions contain the fix?

The issue is fixed in RouterOS 6.49.21, 7.23.4, and 7.24.2.

Published Sep 5, 2026

Updated

MikroTik RouterOS accepts malformed RSA/PKCS#1 v1.5 signatures during X.509 validation. 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.

This issue was fixed in versions: 6.49.21 (Lont-term), 7.23.4 (Lont-term) and 7.24.2 (Stable)

Affected Software

1 affected component

Mikrotik RouterOS<6.49.21, <7.23.4, <7.24.2

Remediation

Recommended actions to resolve this vulnerability, in priority order.

Upgrade
Upgrade MikroTik RouterOS to a version that resolves this vulnerability.
Fixed in 6.49.21
Upgrade
Upgrade MikroTik RouterOS to a version that resolves this vulnerability.
Fixed in 7.23.4
Upgrade
Upgrade MikroTik RouterOS to a version that resolves this vulnerability.
Fixed in 7.24.2

Event History

Sep 5, 2026

CVE Published

via MITRE·08:00 PM

Data Sourced

via MITRE·08:00 PM

DescriptionWeakness

Frequently Asked Questions

Which RouterOS connections are exposed to this attack?

Outbound TLS connections are exposed when an attacker can control or redirect the RouterOS device's connection to the intended server.

Does an attacker need the trusted root CA's private key?

No. The attacker can use the root CA's public certificate to forge a trusted intermediate certificate and issue certificates for arbitrary hostnames.

Which versions contain the fix?

The issue is fixed in RouterOS 6.49.21, 7.23.4, and 7.24.2.

CVE-2026-67278: TLS server impersonation possible in Mikrotik RouterOS

Affected Software

Remediation

Event History

Frequently Asked Questions

Which RouterOS connections are exposed to this attack?

Does an attacker need the trusted root CA's private key?

Which versions contain the fix?

Company

Resources

Contact

Frequently Asked Questions

Which RouterOS connections are exposed to this attack?

Does an attacker need the trusted root CA's private key?

Which versions contain the fix?