CVE-2026-67277: MikroTik RouterOS Missing Authentication for Critical Function Vulnerability
Advisory generated from the CVE record, CISA, Exploit Observer and VEDAS: what it is, whether it is exploited, who is affected, and how to fix and detect it.
Generated by VEDAS. Scores as of 2026-11-01 19:19 UTC. Rebuilt every few hours from cve-scores, CISA KEV and vedas-signatures. How this works and its limits.
What it is
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)
Description quoted from the CVE record (assigned by CERT-PL, published 2026-09-05).
Weakness: CWE-306 Missing authentication for critical function
How it can be exploited
Exploitable over the network with low attack complexity with no special attack requirements needing no privileges and no user interaction. Impact: confidentiality low, integrity none, availability 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
CISA assessment (SSVC): CISA assesses exploitation as active. Automatable: yes. Technical impact: partial.
- On CISA KEV since
- 2026-09-10
- US federal deadline
- 2026-09-13
- Ransomware use
- Not known
Public exploit evidence (Exploit Observer)
Also known as: BDU:2026-14157, EUVD-2026-72025, GHSA-6q2x-6fhj-r3w8
Exploit Observer has no public exploit code that names this CVE or one of its aliases.
Vulnerability databases and vendor advisories (4)
Catalogue entries, not exploit evidence.
- Vulnerability database or vendor advisory: https://euvd.enisa.europa.eu/enisa/EUVD-2026-72025
- Vulnerability database or vendor advisory: https://github.com/advisories/GHSA-6q2x-6fhj-r3w8
- Vulnerability database or vendor advisory: https://nvd.nist.gov/vuln/detail/CVE-2026-67277
- Vulnerability database or vendor advisory: https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-67277
9 more references returned by Exploit Observer did not name this CVE or an alias, so they are left out.
VEDAS data as of 2026-11-01T17:12 UTC; fetched 2026-11-02.
Live scores
- EPSS
- 0.016
some chance of attack soon - VEDAS
- 0.509
some exploit evidence - On CISA KEV
- Yes, since 2026-09-10
- Detection rule
- None yet
Thin horizontal line: the “likely” (EPSS 0.10) or “strong” (VEDAS 0.90) threshold. Shaded “no data” areas are periods when cve-scores did not publish.
Who is affected
| Product | Affected | Not affected |
|---|---|---|
| Mikrotik RouterOS | from 7.24 before 7.24.2 from 7.0.0 before 7.23.4 from 6.0.0 before 6.49.21 | Not stated |
Version ranges exactly as the CVE record states them. “Before X” means X is the first fixed version.
Exploit Observer also maps it to: mikrotik routeros.
How to fix it
Fixed versions stated in the CVE record: 7.24.2, 7.23.4, 6.49.21.
CISA 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.
Vendor guidance:
- https://mikrotik.com/supportsec/september-2026-vulnerability/ (vendor-advisory)
- https://forum.mikrotik.com/t/6-49-21-long-term-is-released/272802 (release-notes)
- https://forum.mikrotik.com/t/7-23-4-long-term-is-released/272801 (release-notes)
- https://forum.mikrotik.com/t/7-24-2-stable-is-released/272800 (release-notes)
How to detect it
There is no open VEDAS detection rule for this bug yet. It is listed on the detection gaps page if CISA has confirmed attacks.
References
Vendor advisories and patches
- https://mikrotik.com/supportsec/september-2026-vulnerability/ (vendor-advisory)
- https://forum.mikrotik.com/t/6-49-21-long-term-is-released/272802 (release-notes)
- https://forum.mikrotik.com/t/7-23-4-long-term-is-released/272801 (release-notes)
- https://forum.mikrotik.com/t/7-24-2-stable-is-released/272800 (release-notes)
Exploits and technical analysis
- https://cert.pl/en/posts/2026/09/mikrotik-routeros-cve (third-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)
Government sources
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-67277 (government-resource)
Other databases
Where this comes from
This advisory is generated automatically by VEDAS from: CVE.org record, CISA KEV, cve-scores (EPSS and VEDAS), Exploit Observer. Text in quotes is reproduced from the source; everything else is a fixed template filled with source fields. Nothing here is written by a language model. Check the vendor advisory before acting, and read how VEDAS and Exploit Observer work, and their limits.