CVE-2026-67278
TLS server impersonation possible in Mikrotik RouterOS
MEDIUM 6.3EPSS 0.3%
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 (Long-term), 7.23.4 (Long-term) and 7.24.2 (Stable)
- Affected
- Mikrotik · RouterOS
- CVSS v4.0 CERT
- 6.3 MEDIUM
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X - CVSS v3.1 NVD
- 9.1 CRITICAL
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N - EPSS
- 0.25% chance of exploitation in the next 30 days, 16th percentile
- Published
- 2026-09-05
- Updated
- 2026-09-17
Proof-of-concept exploits (1)
Security advisories
- https://mikrotik.com/supportsec/september-2026-vulnerability
- https://cert.pl/en/posts/2026/09/mikrotik-routeros-cve
- https://cert.pl/en/posts/2026/09/vulnerabilities-in-mikrotik-routeros-actively-exploited
- https://npratley.net/reversing-mikrotiks-silent-patch-the-routeros-7-23-4-fix-they-wouldn…
- https://forum.mikrotik.com/t/7-23-6-long-term-is-released/273139
- https://forum.mikrotik.com/t/7-24-3-stable-is-released/273138