CVE-2026-67277
MikroTik RouterOS Missing Authentication for Critical Function Vulnerability
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)
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. Deadline for federal agencies: 2026-09-13.
3 articles across 3 outlets · first covered Sep 7, 2026 · latest Sep 12, 2026
Coverage timeline
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CISA Flags Actively Exploited MikroTik RouterOS Flaw Exposing Kernelscisa.gov · Sep 10, 2026
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MikroTik Patches Exploited RouterOS Flaws in MikrTrick Attack Chainwww.securityweek.com · Sep 8, 2026
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MikroTik RouterOS Attacks Exploit MikroTrick Flaws for Full Controlsecurityonline.info · Sep 7, 2026