CVE-2026-67276: SSH user impersonation possible in Mikrotik RouterOS
RouterOS does not compare the complete RSA public key when matching an SSH authentication request to an authorized user key, checking the key type and modulus but omitting the exponent. Because signature verification uses the client-supplied key, an attacker knowing an authorized RSA modulus can supply a key with exponent one, forge a valid signature, and open an SSH command channel as the target user without the private key.This issue affects only 7.x branch was fixed in versions: 7.23.4 (Long-term) and 7.24.2 (Stable)
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade
MikroTik RouterOSto a version that resolves this vulnerability.Fixed in 7.23.4 - Upgrade
Upgrade
MikroTik RouterOSto a version that resolves this vulnerability.Fixed in 7.24.2
Event History
Frequently Asked Questions
Which SSH users are exposed to impersonation?
Any user whose authorized SSH key is RSA may be impersonated if an attacker knows that key's modulus. The attacker does not need the corresponding private key.
What does an attacker need to exploit this issue?
The attacker needs the modulus from an authorized RSA public key and SSH access to the affected RouterOS device. They can provide a public key with the same type and modulus but exponent one, then forge a signature accepted for the target user.
Are patched RouterOS releases available?
Yes. The issue is fixed in RouterOS 6.49.21 Long-term, 7.23.4 Long-term, and 7.24.2 Stable.