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CVE-2026-86060: MikroTik RouterOS Improper Neutralization of Argument Delimiters in a Command Vulnerability

In short

MikroTik RouterOS has a weakness classified as argument injection (CWE-88). CISA added it to its Known Exploited Vulnerabilities catalog on 2026-09-10. NVD lists CVSS 4.0 at 9.2 CRITICAL.

What it is

“MikroTik RouterOS contains an improper neutralization of argument delimiters in a command vulnerability which allows an attacker to change the trusted RouterOS policy mask, leading to privilege escalation.” — CISA KEV, retrieved 2026-11-01
“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)” — NVD, retrieved 2026-11-01

Who is affected

MikroTik RouterOS. NVD lists the following versions as affected:

  • Versions from 6.0 inclusive, before 6.49.21
  • Versions from 7.0 inclusive, before 7.23.4
  • Versions from 7.24 inclusive, before 7.24.2

Exploitation status

CISA KEV added: 2026-09-10. Known ransomware campaign use: Not reported by CISA. Due date CISA set for US federal civilian agencies: 2026-09-13.

Scores

NVD CVSS 4.0: 9.2 CRITICAL; vector CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X; source [email protected].

EPSS by FIRST: 6.39%; percentile 93.67; score date 2026-10-31. EPSS estimates the probability of exploitation in the next 30 days.

CWE: CWE-88.

Timeline

Source events
DateEvent
2026-09-05T20:17:18.703NVD published
2026-09-10CISA KEV added
2026-09-11T12:52:16.507NVD last modified
2026-09-13CISA KEV due
2026-10-31FIRST EPSS score

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.” — CISA KEV

What to do

  • Confirm whether you run MikroTik RouterOS and which version.
  • Apply the vendor update or mitigation in the advisory.
  • Follow CISA’s required action.
  • Review the vendor guidance on signs of compromise.
  • Track the fix through completion.

References

Sources and dates

CISA Known Exploited Vulnerabilities Catalog, version 2026.10.30; retrieved 2026-11-01. CISA KEV data: CC0 1.0. No endorsement by CISA.

NVD retrieved: 2026-11-01. This product uses the NVD API but is not endorsed or certified by the NVD.

EPSS scores by FIRST; score date 2026-10-31.

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