CVE-2026-67277

high · 8.8Actively exploited

On the CISA Known Exploited Vulnerabilities catalog

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.

Added 2026-09-10Remediation due 2026-09-13

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)

8.8

CVSS

1.6%

EPSS (exploit prob.)

75th

EPSS percentile

2026-09-05

Published

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Weaknesses

CWE-306

Affected products

Vendor	Product	Affected versions
mikrotik	routeros	>= 6.0, < 6.49.21
mikrotik	routeros	>= 7.0, < 7.23.4
mikrotik	routeros	>= 7.24, < 7.24.2

Check a specific version with /api/v1/cve/match.

References

Query this programmatically:

curl https://evil-db.io/api/v1/cve/CVE-2026-67277