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 breakdown
CVSS 4.0
Attack Vector
Network
Attack Complexity
Low
Attack Requirements
Present
Privileges Required
None
User Interaction
None
Confidentiality (Vulnerable System)
Low
Integrity (Vulnerable System)
Low
Availability (Vulnerable System)
None
Confidentiality (Subsequent System)
None
Integrity (Subsequent System)
None
Availability (Subsequent System)
None
Affected products
- MikroTik / RouterOS7.24 – 7.24.2
- MikroTik / RouterOS7.0.0 – 7.23.4
- MikroTik / RouterOS6.0.0 – 6.49.21
- MikroTik / RouterOS7.24 – 7.24.3
- MikroTik / RouterOS7.0.0 – 7.23.6
References
- MISChttps://cert.pl/en/posts/2026/09/mikrotik-routeros-cve
- MISChttps://cert.pl/en/posts/2026/09/vulnerabilities-in-mikrotik-routeros-actively-exploited/
- MISChttps://npratley.net/reversing-mikrotiks-silent-patch-the-routeros-7-23-4-fix-they-wouldnt-explain/
- MISChttps://mikrotik.com/supportsec/september-2026-vulnerability/
- MISChttps://forum.mikrotik.com/t/7-23-6-long-term-is-released/273139
- MISChttps://forum.mikrotik.com/t/7-24-3-stable-is-released/273138
Updated 7m ago · 8 sources