CVE-2026-67279: SSH Pre-Authentication Rekey State Bypass in MikroTik RouterOS
In CISA’s Known Exploited Vulnerabilities catalog: Mikrotik RouterOS Improper Enforcement of Behavioral Workflow Vulnerability.
Added , federal remediation due . Known ransomware use: Unknown.
Required action: 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.
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)
Vector CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N · CWE-841
Status incidents that name it
No tracked status incident names this CVE.
Affected vendors and products
Mikrotik: RouterOS
References
- CVE record on cve.org (opens in new tab)
- NVD entry (opens in new tab)
- cert.pl/en/posts/2026/09/mikrotik-routeros-cve (opens in new tab)
- cert.pl/en/posts/2026/09/vulnerabilities-in-mikrotik-routeros-actively-exploi… (opens in new tab)
- forum.mikrotik.com/t/6-49-21-long-term-is-released/272802 (opens in new tab)
- forum.mikrotik.com/t/7-23-4-long-term-is-released/272801 (opens in new tab)
- forum.mikrotik.com/t/7-24-2-stable-is-released/272800 (opens in new tab)
- mikrotik.com/supportsec/september-2026-vulnerability/ (opens in new tab)
- npratley.net/reversing-mikrotiks-silent-patch-the-routeros-7-23-4-fix-they-wouldnt… (opens in new tab)
- CVE records from the CVE Program (cve.org). CVE® is a registered trademark of The MITRE Corporation. (opens in new tab)
- This product uses data from the NVD API but is not endorsed or certified by the NVD. (opens in new tab)
- Known Exploited Vulnerabilities catalog from CISA. (opens in new tab)
- EPSS scores from FIRST (Exploit Prediction Scoring System). (opens in new tab)