UNKNOWN CISA KEV

CVE-2026-67277

CVSS v3

—

Unknown

EPSS Score

0.4 %

exploit probability

CISA KEV

Yes

known exploited

Exploitation

—

SSVC status

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-t

CISA Known Exploited Vulnerability

Date Added: 2026-09-10
Patch Due Date: 2026-09-13
Ransomware Use: Unknown

Technical details

Published: 2026-09-05
Last Modified: 2026-09-05

Frequently asked questions

What is CVE-2026-67277?

Is CVE-2026-67277 actively exploited?

Yes. CVE-2026-67277 is on the CISA Known Exploited Vulnerabilities (KEV) catalog, meaning it has been confirmed as actively exploited in the wild. CISA requires federal agencies to patch by 2026-09-13.

What is the CVSS score for CVE-2026-67277?

A CVSS score has not been assigned to CVE-2026-67277 yet.

Is CVE-2026-67277 affecting your environment?

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