MikroTik RouterOS TLS Forgery: RSA PKCS#1 v1.5 Signature (e=3) Pre-6.49.21
CVE-2026-67278 Published on September 5, 2026
TLS server impersonation possible in Mikrotik RouterOS
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 roots 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)
Vulnerability Analysis
CVE-2026-67278 is exploitable with network access, and does not require authorization privileges or user interaction. This vulnerability is considered to have a low attack complexity. The potential impact of an exploit of this vulnerability is considered to have no impact on confidentiality and integrity and availability.
Weakness Type
Improper Verification of Cryptographic Signature
The software does not verify, or incorrectly verifies, the cryptographic signature for data.
Products Associated with CVE-2026-67278
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Affected Versions
Mikrotik RouterOS:- Version 7.24 and below 7.24.2 is affected.
- Version 7.0.0 and below 7.23.4 is affected.
- Version 6.0.0 and below 6.49.21 is affected.