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CVE-2026-67277: Kernel memory disclosure and denial of service in MikroTik RouterOS btest service

High · CVSS 8.2 (CVSS 3.1)KEV known exploitedEPSS 1.6%, 75th percentilePublished Updated Assigner: CERT-PL

In CISA’s Known Exploited Vulnerabilities catalog: MikroTik RouterOS Missing Authentication for Critical Function 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 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)

Vector CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:H · CWE-306

Status incidents that name it

No tracked status incident names this CVE.

Affected vendors and products

Mikrotik: RouterOS

References

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