CVE-2026-86060

Critical9.8 Published on Sep 5, 2026

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

  • In the CISA exploited-vulnerabilities catalogue since Sep 10, 2026
  • US federal agencies must remediate it by Sep 13, 2026 (BOD 22-01)
  • Attacked 1 day before the vulnerability was made public

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.

Source: CISA KEV · Sep 22, 2026 Sep 11, 2026 Sep 10, 2026 Sep 6, 2026 Sep 5, 2026 Sep 5, 2026

CVSS score9.8 / 10CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Weakness type (CWE)CWE-88
Vendorsmikrotik

Affected products

VendorsProductVersions
mikrotikrouteros< 6.49.21

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