Summary
generated automatically from NVD dataMikroTik RouterOS has an argument-handling flaw (CWE-88) in its SSH login path, triggered by usernames beginning with a prohibited character. It lets the trusted RouterOS policy mask be changed, leading to privilege escalation, and an unauthenticated SSH session reaching the login helper is enough to exploit it. The flaw is listed in the CISA KEV catalog and rated CRITICAL (CVSS v3.1 9.8); it was fixed in 6.49.21 (Long-term), 7.23.4 (Long-term) and 7.24.2 (Stable).
NVD description
RouterOS contains an argument-handling flaw in the SSH login path involving usernames that begin with a prohibited character, allowing for the trusted RouterOS policy mask to be changed, leading to privilege escalation. Exploitation requires an unauthenticated SSH session to reach the RouterOS login helper.This issue was fixed in versions: 6.49.21 (Long-term), 7.23.4 (Long-term) and 7.24.2 (Stable)
⚠️ Actively exploited — CISA KEV
This CVE was added to CISA's Known Exploited Vulnerabilities catalog on 2026-09-10. It is confirmed exploited in the wild and must be patched as a priority.
Remediation deadline (US federal agencies): 2026-09-13
EPSS · FIRST.org
6.4%probability of exploitation in the next 30 days
Higher than 93% of scored CVEs
EPSS (Exploit Prediction Scoring System) estimates, from observed exploitation activity, how likely a CVE is to be exploited in the next 30 days. It complements CVSS, which measures severity, not likelihood. Score of 2026-10-19, recomputed daily by FIRST.org.
In-depth analysis on cveo.tech
We've published a detailed analysis of this CVE — exploitation, IOCs and mitigation.
CVSS v3.1 Score
Information
- Published
- 5 sept. 2026
- Updated
- 11 sept. 2026
- Status
- Analyzed
- Source
- cvd@cert.pl
Affected products
Weaknesses (CWE)
References (8)
- 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/MitigationThird Party Advisory
- https://npratley.net/reversing-mikrotiks-silent-patch-the-routeros-7-23-4-fix-they-wouldnt-explain/ExploitThird Party Advisory
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-86060US Government Resource
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