CVE-2026-67278

  1. OpenCVE
  2. Vulnerabilities (CVE)
  3. CVE-2026-67278
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.

9.1 /10

CVSS v3 : CRITICAL

V3 Legend

Vector :

Exploitability : 3.9 / Impact : 5.2

Attack Vector NETWORK

Attack Complexity LOW

Privileges Required NONE

User Interaction NONE

Confidentiality Impact HIGH

Integrity Impact HIGH

Availability Impact NONE

Scope UNCHANGED

References
Link Resource
https://cert.pl/en/posts/2026/09/mikrotik-routeros-cve Third Party Advisory
https://cert.pl/en/posts/2026/09/vulnerabilities-in-mikrotik-routeros-actively-exploited/ Mitigation Third Party Advisory
https://forum.mikrotik.com/t/7-23-6-long-term-is-released/273139 Release Notes
https://forum.mikrotik.com/t/7-24-3-stable-is-released/273138 Release Notes
https://mikrotik.com/supportsec/september-2026-vulnerability/ Vendor Advisory
https://npratley.net/reversing-mikrotiks-silent-patch-the-routeros-7-23-4-fix-they-wouldnt-explain/ Exploit Third Party Advisory
Configurations

Configuration 1 (hide)

OR cpe:2.3:o:mikrotik:routeros:*:*:*:*:*:*:*:*
cpe:2.3:o:mikrotik:routeros:*:*:*:*:*:*:*:*
History

25 Sep 2026, 14:56

Type Values Removed Values Added
First Time Mikrotik routeros
Mikrotik
References () https://cert.pl/en/posts/2026/09/mikrotik-routeros-cve - () https://cert.pl/en/posts/2026/09/mikrotik-routeros-cve - Third Party Advisory
References () https://cert.pl/en/posts/2026/09/vulnerabilities-in-mikrotik-routeros-actively-exploited/ - () https://cert.pl/en/posts/2026/09/vulnerabilities-in-mikrotik-routeros-actively-exploited/ - Mitigation, Third Party Advisory
References () https://forum.mikrotik.com/t/7-23-6-long-term-is-released/273139 - () https://forum.mikrotik.com/t/7-23-6-long-term-is-released/273139 - Release Notes
References () https://forum.mikrotik.com/t/7-24-3-stable-is-released/273138 - () https://forum.mikrotik.com/t/7-24-3-stable-is-released/273138 - Release Notes
References () https://mikrotik.com/supportsec/september-2026-vulnerability/ - () https://mikrotik.com/supportsec/september-2026-vulnerability/ - Vendor Advisory
References () https://npratley.net/reversing-mikrotiks-silent-patch-the-routeros-7-23-4-fix-they-wouldnt-explain/ - () https://npratley.net/reversing-mikrotiks-silent-patch-the-routeros-7-23-4-fix-they-wouldnt-explain/ - Exploit, Third Party Advisory
CVSS v2 : unknown
v3 : unknown 		v2 : unknown
v3 : 9.1
CPE cpe:2.3:o:mikrotik:routeros:*:*:*:*:*:*:*:*

17 Sep 2026, 15:16

Type Values Removed Values Added
Summary (en) 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. (en) 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.

17 Sep 2026, 14:17

Type Values Removed Values Added
Summary (en) 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 affects only 7.x branch was fixed in versions: 7.23.4 (Long-term) and 7.24.2 (Stable) (en) 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.
References
  • {'url': 'https://forum.mikrotik.com/t/7-23-4-long-term-is-released/272801', 'source': 'cvd@cert.pl'}
  • {'url': 'https://forum.mikrotik.com/t/7-24-2-stable-is-released/272800', 'source': 'cvd@cert.pl'}
  • () 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 -
Information

Published : 2026-09-05 20:17

Updated : 2026-09-25 14:56

NVD link : CVE-2026-67278

Mitre link : CVE-2026-67278

CVE.ORG link : CVE-2026-67278

JSON object : View

Products Affected

mikrotik

  • routeros
CWE
CWE-347

Improper Verification of Cryptographic Signature