Actively exploited · Published Sep 5, 2026 · Assigned by CERT-PL

CVE-2026-67279SSH Pre-Authentication Rekey State Bypass in MikroTik RouterOS

Medium 6.9 Exploited

In plain English

A medium-severity security flaw in RouterOS from Mikrotik. Attackers are actively exploiting it in the wild (listed by CISA on September 25, 2026). The chance it is exploited in the next 30 days is estimated at 2.3% (higher than 83% of all known vulnerabilities). Ready-made attack tooling exists: public proof-of-concept code. Apply mitigations in accordance with vendor instructions, ensuring compliance with CISA’s BOD 26-04 Prioritizing Security Updates Based on Risk (see URL in Notes) guidance and CISA’s “Forensics Triage Requirements” (see URL in Notes). Follow applicable BOD 26-04 guidance for cloud services or discontinue use of the product if mitigations are unavailable. Stakeholders are responsible for evaluating each asset's internet exposure and ensuring adherence to BOD 26-04 patching guidelines.

Severity (CVSS 4.0)6.9Medium
Exploit odds (30 days)2.3%top 16.8% of all CVEs
Exploited in the wildYesCISA KEV since Sep 25, 2026
Attack tooling1Public PoC

CISA guidance

Apply mitigations in accordance with vendor instructions, ensuring compliance with CISA’s BOD 26-04 Prioritizing Security Updates Based on Risk (see URL in Notes) guidance and CISA’s “Forensics Triage Requirements” (see URL in Notes). Follow applicable BOD 26-04 guidance for cloud services or discontinue use of the product if mitigations are unavailable. Stakeholders are responsible for evaluating each asset's internet exposure and ensuring adherence to BOD 26-04 patching guidelines.

Federal agencies must remediate by Sep 28, 2026.

Official 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)

Affected products (as reported)

VendorProductVersions
Mikrotik RouterOS 7.24 – before 7.24.27.0.0 – before 7.23.46.0.0 – before 6.49.21

Weakness: CWE-841 · Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N

References