CVE-2026-67277
Description
RouterOS accepts a "related" btest connection before the corresponding primary session has completed authentication. An unauthenticated client can use this state to start an IPv4 UDP test. With "random-data=false", the sender transmits an uninitialized tail from a kernel packet buffer. A separate unchecked, inverted packet-size interval causes unsigned integer underflow, anomalously large fragmented output, and can restart the RouterOS kernel. This issue was fixed in versions: 6.49.21 (Long-term), 7.23.4 (Long-term) and 7.24.2 (Stable)
How to fix
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.
CISA due date: Sep 13, 2026- mikrotik routeros6.49.21, 7.23.4, 7.24.2 or later
Affected products
| Product | Affected versions | Fixed in |
|---|---|---|
| mikrotik routeros | 6.0 ≤ v < 6.49.21, 7.0 ≤ v < 7.23.4, 7.24 ≤ v < 7.24.2 | 6.49.21, 7.23.4, 7.24.2 |
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