CVE-2026-67277

MikroTik RouterOS: Missing Authentication for Critical Function

As of , CVE-2026-67277 in MikroTik RouterOS is on CISA's list of exploited vulnerabilities: CISA listed it on . Our patch-first group: Patch soon.

Exploited
Yes: CISA listed it on 10 September 2026
US federal deadline
13 September 20263 days after CISA listed it. US federal civilian agencies must fix it by then.
Used in ransomware campaigns
Not known to CISA
EPSS score
0.02Higher than 74% of the CVEs EPSS scores. EPSS estimates the chance of exploitation activity in the next 30 days.
Public exploit
None foundNeither Metasploit nor Exploit-DB lists one.
Fix
Vendor advice: mikrotik.comLinks below, from CISA's entry.

What CISA says to do

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's required action

What the flaw is

MikroTik RouterOS contains a missing authentication for critical function vulnerability which allows kernel memory disclosure and denial of service in the btest service.

CISA's 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)

The CVE record's description, from CERT-PL

CVE published
5 September 2026
Assigned by
CERT-PL
CVSS
8.8 High (CVSS 4.0, from the CNA)
CWE-306
Missing Authentication for Critical Function
CISA SSVC, exploitation
active
CISA SSVC, automatable
yes
CISA SSVC, technical impact
partial

Timeline

  1. The CVE record was published.
  2. CISA added it to its list of exploited vulnerabilities.
  3. The US federal deadline to fix it.
  4. CISA changed its entry. Edited: description.

RouterOS: other exploited entries

VulnerabilityProductOur groupListedDeadlineEPSS
CVE-2026-86060Improper Neutralization of Argument Delimiters in a CommandMikroTik RouterOSPatch nowForensic triage required by CISA0.06
CVE-2026-67279Improper Enforcement of Behavioral WorkflowMikroTik RouterOSPatch nowListed in the last 14 days0.01
CVE-2018-14847Router OS Directory TraversalMikroTik RouterOSPatch this weekMetasploit module; EPSS 0.960.96
CVE-2018-7445Stack-Based Buffer OverflowMikroTik RouterOSPatch this weekEPSS 0.610.61

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