Vulnerability · Published Sep 5, 2026 · Assigned by CERT-PL
CVE-2026-67276SSH user impersonation possible in Mikrotik RouterOS
Critical 9.2
In plain English
A critical-severity security flaw in RouterOS from Mikrotik. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 8.9% (higher than 95% of all known vulnerabilities). Ready-made attack tooling exists: public proof-of-concept code.
Official description
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 products (as reported)
Weakness: CWE-347 · Vector: CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
References
- 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/ technical-description
- https://npratley.net/reversing-mikrotiks-silent-patch-the-routeros-7-23-4-fix-they-wouldnt-explain/ exploit
- https://mikrotik.com/supportsec/september-2026-vulnerability/ vendor-advisory
- https://forum.mikrotik.com/t/7-23-4-long-term-is-released/272801 release-notes
- https://forum.mikrotik.com/t/7-24-2-stable-is-released/272800 release-notes