RouterOS fails to compare the full RSA public key when authenticating SSH requests, checking only the key type and modulus but ignoring the exponent. An attacker who knows an authorized RSA modulus can supply a key with an exponent of one, forge a valid signature, and consequently open an SSH command channel as the target user. This allows the attacker to run arbitrary commands with the privileges of the impersonated account, effectively achieving remote code execution on the device.

The vulnerability affects Mikrotik RouterOS versions older than 6.49.21 for long‑term, 7.23.4 for long‑term, and 7.24.2 for stable releases. Any device running these older releases is susceptible if RSA key authentication is enabled for any user.

With a CVSS score of 9.2 the vulnerability is considered critical. Although no EPSS score is published, industry advisories have reported active exploitation in the wild. The attack vector is remote, requiring an attacker to establish an SSH session and supply a forged key. If the attacker can obtain the public‑key modulus (e.g., from captive portals or leaked backups), the exploit can be executed without the private key, allowing full impersonation of the target user.