CVE-2026-67277
Kernel memory disclosure and denial of service in MikroTik RouterOS btest service
- State
- Published
- Severity
- 8.8 High
- Published
- Sep 5, 2026
- Updated
- Sep 11, 2026
- Reserved
- Jul 29, 2026
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)
Scores
| CVSS | Score | Vector | Source |
|---|---|---|---|
| 4.0 | 8.8 High | 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 |
Weaknesses
- CWE-306 Missing authentication for critical function
Affected Products
| Product | Versions |
|---|---|
RouterOSMikrotik |
|
References
- https://cert.pl/en/posts/2026/09/mikrotik-routeros-cvethird-party-advisory
- https://cert.pl/en/posts/2026/09/vulnerabilities-in-mikrotik-routeros-actively-exploited/technical-description
- https://npratley.net/reversing-mikrotiks-silent-patch-the-routeros-7-23-4-fix-they-wouldnt-explain/exploit
- https://mikrotik.com/supportsec/september-2026-vulnerability/vendor-advisory
- https://forum.mikrotik.com/t/6-49-21-long-term-is-released/272802release-notes
- https://forum.mikrotik.com/t/7-23-4-long-term-is-released/272801release-notes
- https://forum.mikrotik.com/t/7-24-2-stable-is-released/272800release-notes
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-67277government-resource
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