CVE-2026-67277Kernel memory disclosure and denial of service in MikroTik RouterOS btest service
Updated under an hour ago ()
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It affects Mikrotik RouterOS. Add what you run to find out whether that includes you.
CISA lists it as known exploited since Sep 10, 2026; federal agencies had to remediate by Sep 13, 2026. Treat that date as your deadline.
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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)
- CVSS
- 8.8 HIGH (v4.0, CNA)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
- Weakness (CWE)
- CWE-306
- Known exploited
- Added to CISA KEV Sep 10, 2026; federal remediation due Sep 13, 2026Apply 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.
- EPSS (exploitation in the next 30 days)
- 1.56% (percentile 75)
- Assigned by
- CERT-PL
- NVD analysis
- Analyzed
- Record last updated
- Sep 11, 2026
- First seen by InfoSec Signals
- Oct 9, 2026
Affected products
Mikrotik RouterOS mikrotik:routeros (from the name) | from 7.24 before 7.24.2; from 7.0.0 before 7.23.4; from 6.0.0 before 6.49.21 | CNA record |
mikrotik routeros mikrotik:routeros | from 6.0 before 6.49.21; from 7.0 before 7.23.4; from 7.24 before 7.24.2 | NVD |
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, mitigation, third-party-advisory
- https://npratley.net/reversing-mikrotiks-silent-patch-the-routeros-7-23-4-fix-they-wouldnt-explain/exploit, third-party-advisory
- 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-2026-67277us-government-resource
The CVE record on cve.org NVD's entry
The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.