Kernel memory disclosure and denial of service in MikroTik RouterOS btest service
Published Sep 5, 2026 ·Due Sep 13, 2026
8.8
HIGHCVSS 4.0
EPSS 1.56%
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)
Affected products
-
- Version 6.0.0StatusaffectedConstraints<6.49.21
- Version 7.0.0StatusaffectedConstraints<7.23.4
- Version 7.24StatusaffectedConstraints<7.24.2
- Version
No data.
No Red Hat product state for this CVE.
No package ranges for this CVE.
Remediation
No remediation recorded yet.
Metrics
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
1 other source (NVD) ▾
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
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:H
No CVSS v3.0 score for this CVE.
No CVSS v2.0 score for this CVE.
Date Added
Sep 10, 2026
Patch Due
Sep 13, 2026
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.
CISA SSVC (Vulnrichment)
Stakeholder-Specific Vulnerability Categorization from CISA ADP.
Exploitation
ActiveAutomatable
YesTechnical Impact
PartialDecision
n/aAssessed Sep 10, 2026 · SSVC 2.0.3
Estimated probability of exploitation in the wild in the next 30 days (FIRST EPSS). As of Oct 1, 2026.
Score over time
Sep–Oct 2026- EPSS v5
Percentile over time
- EPSS v5
Table of values (2 key points)
Flat stretches are collapsed; showing up to 120 newest points.
| Date | Score | Percentile | Model |
|---|---|---|---|
| Oct 1, 2026 | 1.56% (0.01560) | 74.33th | v5 (v2026.06.15) |
| Sep 6, 2026 | 0.43% (0.00435) | 36.55th | v5 (v2026.06.15) |
References (8)
- https://cert.pl/en/posts/2026/09/mikrotik-routeros-cve third-party-advisoryThird Party Advisory
- https://cert.pl/en/posts/2026/09/vulnerabilities-in-mikrotik-routeros-actively-exploited/ technical-descriptionMitigationThird Party Advisory
- https://forum.mikrotik.com/t/6-49-21-long-term-is-released/272802 release-notesRelease Notes
- https://forum.mikrotik.com/t/7-23-4-long-term-is-released/272801 release-notesRelease Notes
- https://forum.mikrotik.com/t/7-24-2-stable-is-released/272800 release-notesRelease Notes
- https://mikrotik.com/supportsec/september-2026-vulnerability/ vendor-advisoryVendor Advisory
- https://npratley.net/reversing-mikrotiks-silent-patch-the-routeros-7-23-4-fix-they-wouldnt-explain/ exploitThird Party Advisory
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-67277 government-resourceUS Government Resource
| Link | Providers | Tags |
|---|---|---|
| https://cert.pl/en/posts/2026/09/mikrotik-routeros-cve | third-party-advisoryThird Party Advisory | |
| https://cert.pl/en/posts/2026/09/vulnerabilities-in-mikrotik-routeros-actively-exploited/ | technical-descriptionMitigationThird Party Advisory | |
| https://forum.mikrotik.com/t/6-49-21-long-term-is-released/272802 | release-notesRelease Notes | |
| https://forum.mikrotik.com/t/7-23-4-long-term-is-released/272801 | release-notesRelease Notes | |
| https://forum.mikrotik.com/t/7-24-2-stable-is-released/272800 | release-notesRelease Notes | |
| https://mikrotik.com/supportsec/september-2026-vulnerability/ | vendor-advisoryVendor Advisory | |
| https://npratley.net/reversing-mikrotiks-silent-patch-the-routeros-7-23-4-fix-they-wouldnt-explain/ | exploitThird Party Advisory | |
| https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-67277 | government-resourceUS Government Resource |
Change history (0)
No recorded changes yet.