CVE-2026-67277
MikroTik RouterOS Missing Authentication for Critical Function Vulnerability
This vulnerability is in the CISA Known Exploited Vulnerabilities catalog: attackers are using it. If you run RouterOS, fix it now.
CISA 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.
US federal civilian agencies must remediate by Sep 13, 2026.
Patch status
No official fix confirmed yet
Until a fix ships, follow the vendor's mitigations and CISA's required action, limit exposure of affected systems, and watch this record for a patch.
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)
Source: NIST National Vulnerability Database. Official vulnerability data, reproduced as published.
Affected products
| Product | Vendor | Affected versions | Fixed in | Source |
|---|---|---|---|---|
| RouterOS | MikroTik | >= 6.0, < 6.49.21; >= 7.0, < 7.23.4; >= 7.24, < 7.24.2 | 6.49.21; 7.23.4; 7.24.2 | KEV |
Sources: KEV = CISA Known Exploited Vulnerabilities catalog.
Intelligence timeline
Developments from the last 30 days, newest first.
- CVSS scoredUpdateKEV
CVE-2026-67277 scored CVSS 8.8: MikroTik RouterOS, MikroTik RouterOS Missing Authentication for Critical Function Vulnerability
CISA lists this as exploited in the wild. Unpatched RouterOS systems are exposed to active attacks now.
Basis: NIST National Vulnerability Database
- Added to CISA KEV
CVE-2026-67277 added to CISA KEV: MikroTik RouterOS, MikroTik RouterOS Missing Authentication for Critical Function Vulnerability
CISA lists this as exploited in the wild. Unpatched RouterOS systems are exposed to active attacks now.
Basis: CISA Known Exploited Vulnerabilities catalog
Coverage
We have not published a story about this vulnerability yet.