CVE-2026-67277
Kernel memory disclosure and denial of service in MikroTik RouterOS btest service
At a glance
- Source
- NVD
- EPSS
- EPSS 1.56 % · percentile 75 ()
- State
- PUBLISHED
- Published
- Updated
- Assigner
- CERT-PL
- NVD status
- Analyzed
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)
Weaknesses (CWE)
- CWE-306 — Missing Authentication for Critical Functionality
References
- https://cert.pl/en/posts/2026/09/mikrotik-routeros-cve
- https://cert.pl/en/posts/2026/09/vulnerabilities-in-mikrotik-routeros-actively-exploited/
- https://npratley.net/reversing-mikrotiks-silent-patch-the-routeros-7-23-4-fix-they-wouldnt-explain/
- https://mikrotik.com/supportsec/september-2026-vulnerability/
- https://forum.mikrotik.com/t/6-49-21-long-term-is-released/272802
- https://forum.mikrotik.com/t/7-23-4-long-term-is-released/272801
- https://forum.mikrotik.com/t/7-24-2-stable-is-released/272800
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-67277
Scores
| Version | Score | Vector | Scored by |
|---|---|---|---|
| CVSS 4.0 | HIGH 8.8 | 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 | CERT-PL |
| CVSS 4.0 | HIGH 8.8 | 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 | NVD · cvd@cert.pl (Secondary) |
| CVSS 3.1 | HIGH 8.2 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:H | NVD · nvd@nist.gov (Primary) |
European references
- ENISA EUVD · EUVD-2026-72025
- GCVE · GCVE-0-2026-67277
Affected configurations (NVD CPE)
cpe:2.3:o:mikrotik:routeros:*:*:*:*:*:*:*:*≥ 6.0 < 6.49.21cpe:2.3:o:mikrotik:routeros:*:*:*:*:*:*:*:*≥ 7.0 < 7.23.4cpe:2.3:o:mikrotik:routeros:*:*:*:*:*:*:*:*≥ 7.24 < 7.24.2
Affected products
| Product | Versions |
|---|---|
| Mikrotik · RouterOS | affected 7.24 < 7.24.2 ; affected 7.0.0 < 7.23.4 ; affected 6.0.0 < 6.49.21 |
Sources
| Source | Licence |
|---|---|
| CVE List (CVEProject cvelistV5) | CVE Program Terms of Use |
| CISA Known Exploited Vulnerabilities | CC0 1.0 |
| EPSS (FIRST.org) | FIRST — attribution requested |
| ENISA EUVD | ENISA — reproduction authorised, source acknowledged |
| NVD (NIST) via fkie-cad/nvd-json-data-feeds | Public domain — this product uses data from the NVD API but is not endorsed or certified by the NVD |