8.8
High
CVE-2026-67277 MikroTik RouterOS Missing Authentication for Critical Function Vulnerability
Active exploitation observed
· CISA KEV catalogue
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.
Ransomware campaigns
Not observed so far
Weakness
CWE-306
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)
Affected products and versions
Other CVEs of RouterOS
The 26 CVEs of RouterOS →
CVE-2026-89035
MikroTik RouterOS through 7.24.5 contains a session token replay vulnerability in the WebFig interface that allows…
9.1
Critical
CVE-2026-112158
A weakness has been identified in MikroTik RouterOS up to 6.40.5/6.44/7.20.8
7.1
High
CVE-2026-103903
An incorrect authorization vulnerability in the WinBox authentication flow of MikroTik RouterOS allows a remote…
8.7
High
CVE-2026-84411
The web management service in affected RouterOS versions contains an integer underflow in its HTTP request body handling…
9.8
Critical