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CVE-2026-67279

SSH Pre-Authentication Rekey State Bypass in MikroTik RouterOS

Published: Sep 5, 2026Updated: Sep 8, 2026 Sources: CVE List NVDCWE-841
N/ACVSS
NVD MITRE
EPSS Score
0.4%
Top 61.9%
CISA KEV
Not in KEV
Exploits
No Known Exploits
Remediation
No Fix Available
Self-Check
OpenVAS

Description

RouterOS SSH enters the connection protocol after a client-requested rekey even though user authentication was never attempted, allowing an unauthenticated client to open a session channel and send an exec request. On affected builds the server dispatches the command, enabling unauthenticated creation, overwrite, and reconstruction of files in the RouterOS managed file namespace, including support files containing configuration and diagnostic data.This issue was fixed in versions: 6.49.21 (Long-term), 7.23.4 (Long-term) and 7.24.2 (Stable)

In plain language

AI Act now

RouterOS versions before 6.49.21, 7.23.4, or 7.24.2 can let an outsider run commands without signing in, so small businesses using it should update urgently.

Executive summary

Unauthenticated SSH pre-authentication state bypass via client-requested rekey permits session-channel exec requests and file operations in RouterOS managed storage.

If affected, business impact
Unauthorized router changesConfiguration data exposureDiagnostic file tamperingNetwork service disruption

What to do now

  1. Check each RouterOS device’s installed version and whether its SSH service can be reached from outside your trusted administration network.
  2. Update to RouterOS 6.49.21 on the 6.49 long-term branch, 7.23.4 on the 7.23 long-term branch, or 7.24.2 on the stable branch.
  3. Until updated, disable SSH if unused or restrict it to specific trusted administrator addresses.
  4. Review RouterOS files and administrative activity for unexpected changes after updating.
Usually a quick update

Weaknesses

CWE-841

Affected Products

Mikrotik
commercial·LVaka routeros, winbox
RouterOSOn-premNetwork Device
Networking Infrastructure / router-switch

Exploitability

No known exploits, KEV entries, or remediation guidance available for this vulnerability yet.
Is your org exposed to CVE-2026-67279?Request an assessment to establish which checks are appropriate for your systems. Check my exposure

References

https://cert.pl/en/posts/2026/09/mikrotik-routeros-cve
cert.pl
https://cert.pl/en/posts/2026/09/vulnerabilities-in-mikrotik-routeros-actively-exploited/
cert.pl
https://forum.mikrotik.com/t/6-49-21-long-term-is-released/272802
forum.mikrotik.com
and 4 more references View all →
News mentions
3

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