MikroTik RouterOS Missing Authentication for Critical Function Vulnerability
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…
Severity = CVSS. Probability = EPSS (FIRST). Exploitation = public signals: KEV, EUVD, ransomware, EPSS above 10 %, no account required.
Exploitation probability EPSS · FIRST
Exploitation signals 3 / 5
- KEV catalog (CISA)10 Sept 2026
- Exploited in EUVD (ENISA)05 Sept 2026
- Used by ransomwareno
- EPSS above 10 %1.6%
- No account, over the networkyes
What to do
Fix
Apply the vendor’s fix as soon as it is available.
CISA guidance: 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.
Meanwhile
Take the service off the internet or restrict access to it, watch the logs and look for signs of compromise.
Manufacturers (CRA)
Exploited vulnerability in your product: early warning to ENISA within 24 h, then notification within 72 h (Article 14 of the Cyber Resilience Act). The CRA explained
Description ENISA EUVD
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
- 7.0.0 <7.23.4
- 7.24 <7.24.2
- 6.0.0 <6.49.21
Open source packages OSV
Affected libraries according to OSV, with fixed versions.
Timeline
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Published
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Exploitation reported (ENISA)
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Added to the KEV catalog
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CISA remediation due date
References
Other exploited vulnerabilities from the same vendor
- CVE-2026-67279Mikrotik RouterOS Improper Enforcement of Behavioral Workflow Vulnerability4.6 · Actively exploited
- CVE-2026-86060MikroTik RouterOS Improper Neutralization of Argument Delimiters in a Command Vulnerability5.7 · Actively exploited
- CVE-2026-67276MikroTik RouterOS5.1 · Actively exploited
- CVE-2018-7445MikroTik RouterOS Stack-Based Buffer Overflow Vulnerability8.3 · Background exploitation
- CVE-2018-14847MikroTik Router OS Directory Traversal Vulnerability8.9 · Background exploitation