Kernel memory disclosure and denial of service in MikroTik RouterOS btest service

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-67277
StatePUBLISHED
AssignerCERT-PL
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-09-05 20:17:18 UTC
Updated2026-09-05 21:16:50 UTC
DescriptionRouterOS 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)

Risk And Classification

Primary CVSS: v4.0 8.8 HIGH from [email protected]

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

Problem Types: CWE-306 | CWE-306 CWE-306 Missing authentication for critical function

VersionSourceTypeScoreSeverityVector
4.0[email protected]Secondary8.8HIGHCVSS: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/C...
4.0CNACVSS8.8HIGHCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:N/VA:H/SC:N/SI:N/SA:N

CVSS v4.0 Breakdown

Attack Vector
Network
Attack Complexity
Low
Attack Requirements
None
Privileges Required
None
User Interaction
None
Confidentiality
Low
Integrity
None
Availability
High
Sub Conf.
None
Sub Integrity
None
Sub Availability
None

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

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Mikrotik RouterOS affected 7.24 7.24.2 custom Not specified
CNA Mikrotik RouterOS affected 7.0.0 7.23.4 custom Not specified
CNA Mikrotik RouterOS affected 6.0.0 6.49.21 custom Not specified

References

ReferenceSourceLinkTags
cert.pl/en/posts/2026/09/mikrotik-routeros-cve [email protected] cert.pl
npratley.net/reversing-mikrotiks-silent-patch-the-routeros-7-23-4-fix-they... [email protected] npratley.net
forum.mikrotik.com/t/6-49-21-long-term-is-released/272802 [email protected] forum.mikrotik.com
cert.pl/en/posts/2026/09/vulnerabilities-in-mikrotik-routeros-activel... [email protected] cert.pl
forum.mikrotik.com/t/7-23-4-long-term-is-released/272801 [email protected] forum.mikrotik.com
forum.mikrotik.com/t/7-24-2-stable-is-released/272800 [email protected] forum.mikrotik.com
mikrotik.com/supportsec/september-2026-vulnerability [email protected] mikrotik.com
CVE Program record CVE.ORG www.cve.org canonical
NVD vulnerability detail NVD nvd.nist.gov canonical, analysis

Vendor Comments And Credit

Discovery Credit

CNA: Sławomir Rozbicki (CERT.PL) (en)

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