CVE-2026-67278: TLS server impersonation possible in Mikrotik RouterOS

Medium 6.3 EPSS 0.3% MikroTik RouterOS

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.

What do these terms mean? CVE · CVSS score · exploited (KEV) · EPSS · backported fix · all terms

What to do now

  1. Check whether you run MikroTik RouterOS and which version (commands below).
  2. Install the fixed version for your system: see “Patch it” below.
  3. The router reboots to finish the update; afterwards run /system routerboard upgrade and reboot again if the RouterBOARD firmware changed.

Affected and fixed versions

Affected:

Patch it

Use the commands for your system. Distribution packages often keep an older version number with the fix backported, so compare with the fixed package versions in the table below, not only with the upstream version.

Built from source
RouterOS: /system package update check-for-updates, then /system package update install

General update steps for every system are on the Linux and Unix & BSD pages; after updating, see which services to restart.

Sources

Page generated automatically from official sources on 2026-11-03 18:05 UTC. Always confirm with your vendor's advisory.