TLS server impersonation possible in Mikrotik RouterOS
Summary
| CVE | CVE-2026-67278 |
|---|---|
| State | PUBLISHED |
| Assigner | CERT-PL |
| Source Priority | CVE Program / NVD first with legacy fallback |
| Published | 2026-09-05 20:17:18 UTC |
| Updated | 2026-09-25 14:56:04 UTC |
| 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. |
Risk And Classification
Primary CVSS: v4.0 6.3 MEDIUM from [email protected]
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
EPSS: 0.002520000 probability, percentile 0.149770000 (date 2026-09-27)
Problem Types: CWE-347 | CWE-347 CWE-347 Improper verification of cryptographic signature
| Version | Source | Type | Score | Severity | Vector |
|---|---|---|---|---|---|
| 4.0 | [email protected] | Secondary | 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/C... |
| 4.0 | CNA | CVSS | 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 |
| 3.1 | [email protected] | Primary | 9.1 | CRITICAL | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N |
CVSS v4.0 Breakdown
Attack Vector
NetworkAttack Complexity
LowAttack Requirements
PresentPrivileges Required
NoneUser Interaction
NoneConfidentiality
LowIntegrity
LowAvailability
NoneSub Conf.
NoneSub Integrity
NoneSub Availability
NoneCVSS: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 Breakdown
Attack Vector
NetworkAttack Complexity
LowPrivileges Required
NoneUser Interaction
NoneScope
UnchangedConfidentiality
HighIntegrity
HighAvailability
NoneCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
NVD Known Affected Configurations (CPE 2.3)
Vendor Declared Affected Products
References
| Reference | Source | Link | Tags |
|---|---|---|---|
| cert.pl/en/posts/2026/09/mikrotik-routeros-cve | [email protected] | cert.pl | Third Party Advisory |
| npratley.net/reversing-mikrotiks-silent-patch-the-routeros-7-23-4-fix-they... | [email protected] | npratley.net | Exploit, Third Party Advisory |
| cert.pl/en/posts/2026/09/vulnerabilities-in-mikrotik-routeros-activel... | [email protected] | cert.pl | Mitigation, Third Party Advisory |
| forum.mikrotik.com/t/7-24-3-stable-is-released/273138 | [email protected] | forum.mikrotik.com | Release Notes |
| forum.mikrotik.com/t/7-23-6-long-term-is-released/273139 | [email protected] | forum.mikrotik.com | Release Notes |
| mikrotik.com/supportsec/september-2026-vulnerability | [email protected] | mikrotik.com | Vendor Advisory |
| forum.mikrotik.com/t/6-49-21-long-term-is-released/272802 | MITRE | forum.mikrotik.com | |
| forum.mikrotik.com/t/7-23-4-long-term-is-released/272801 | MITRE | forum.mikrotik.com | |
| forum.mikrotik.com/t/7-24-2-stable-is-released/272800 | MITRE | forum.mikrotik.com | |
| CVE Program record | CVE.ORG | www.cve.org | canonical |
| NVD vulnerability detail | NVD | nvd.nist.gov | canonical, analysis |
Vendor Comments And Credit
Discovery Credit
CNA: Sławomir Rozbicki (CERT.PL) (en)
CNA: Robert Żegleń (en)
There are currently no legacy QID mappings associated with this CVE.