High severity · published Sep 5, 2026
CVE-2026-67277
Kernel memory disclosure and denial of service in MikroTik RouterOS btest service
In wildKEV
8.2
CVSS
1.6%
EPSS
Yes
On KEV
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)
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:H
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Confidentiality
Low
Integrity
None
Availability
High
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)1.6% · higher than 75% of CVEs
Exploited in the wildYes
CISA KEVListed Sep 10, 2026
Federal remediation dueSep 13, 2026
Ransomware campaign useNot known
Affected products
Which versions
RO
RouterOS · Mikrotik
7.24 before 7.24.2; 7.0.0 before 7.23.4; 6.0.0 before 6.49.21 · source: vendor, NVD, KEV
In the news
AdvisoryHigh
CISA Adds Two Known Exploited Vulnerabilities to Catalog
CISA has added two new vulnerabilities to its Known Exploited Vulnerabilities (KEV) Catalog , based on evidence of active exploitation.
CVE-2026-67277 MikroTik RouterOS Missing Authentication for Critical Function Vulnerability
CVE-2026-86060 MikroTik RouterOS Improper Neutralization of Argument Delimiters in a Command Vulnerability
These types of vulnerabilities are a frequent attack vector for malicious cyber actors and pose significant risks to the federal enterprise.
Binding Operational Directive (BOD) 26-04: Prioritizing Security Updates Based on Risk establishes vulnerability management requirements for Federal Civilian Executive Branch (FCEB) agencies. BOD 26-04 reinforces the importance of the KEV Catalog and requires federal agencies to prioritize rapid remediation of high-risk vulnerabilities, specifically those identified by Common Vulnerabilities and Exposures (CVEs) listed in CISA’s KEV Catalog on publicly exposed assets that grant total control of the asset post-exploitation, while deferring action for lower-risk vulnerabilities. BOD 26-04 further establishes basic expectations for when agencies must check whether threat actors compromised the system before the patch was applied.
While BOD 26-04 applies only to FCEB agencies, CISA encourages all organizations to adopt risk-based vulnerability management and prioritize remediation of KEV Catalog vulnerabilities . CISA will continue to add vulnerabilities to the catalog that meet the specifi...
Sep 10, 2026·CISA Advisories
VulnerabilityHigh
[CISA KEV] CVE-2026-67277: MikroTik RouterOS - MikroTik RouterOS Missing Authentication for Critical Function Vulnerability
MikroTik RouterOS contains a missing authentication for critical function vulnerability which allows kernel memory disclosure and denial of service in the btest service.
RORouterOSCVE-2026-67277
Sep 10, 2026·CISA KEV
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-67277
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-67277
CISA KEV catalogue
https://www.cisa.gov/known-exploited-vulnerabilities-catalog
third-party-advisory
https://cert.pl/en/posts/2026/09/mikrotik-routeros-cve
technical-description
https://cert.pl/en/posts/2026/09/vulnerabilities-in-mikrotik-routeros-actively-exploited/
exploit
https://npratley.net/reversing-mikrotiks-silent-patch-the-routeros-7-23-4-fix-they-wouldnt-explain/
vendor-advisory
https://mikrotik.com/supportsec/september-2026-vulnerability/
release-notes
https://forum.mikrotik.com/t/6-49-21-long-term-is-released/272802
release-notes
https://forum.mikrotik.com/t/7-23-4-long-term-is-released/272801
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