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

CVE-2026-86060 is rated critical with a CVSS v3.1 base score of 9.8 and affects MikroTik RouterOS. Per its scoring, it can be exploited over the network, without authentication, without any user interaction. The scored impact on confidentiality, integrity and availability is the highest available. CISA added it to its Known Exploited Vulnerabilities catalog on 2026-09-10, which means exploitation in the wild has been observed.

Vulnerability 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)

Severity breakdown

CVSS v3.1 9.8: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

• Attack vector: Network. Exploitable remotely over the network, with no need for local or physical access.
• Attack complexity: Low. No special conditions; the attack can be repeated reliably.
• Privileges required: None. No account or prior access is needed.
• User interaction: None. No action from any user is needed.
• Scope: Unchanged. Impact stays within the vulnerable component.
• Confidentiality impact: High. Total loss of confidentiality; sensitive data can be fully disclosed.
• Integrity impact: High. Total loss of integrity; data or system state can be fully modified.
• Availability impact: High. Total loss of availability; the component can be shut down.

Underlying weakness

CWE-88: Improper Neutralization of Argument Delimiters in a Command

The product constructs a string for a command to be executed by a separate component in another control sphere, but it does not properly delimit the intended arguments, options, or switches within that command string.

Affected products

• Mikrotik Routeros: from 6.0 before 6.49.21; from 7.0 before 7.23.4; from 7.24 before 7.24.2

References

• https://mikrotik.com/supportsec/september-2026-vulnerability/
• https://cert.pl/en/posts/2026/09/vulnerabilities-in-mikrotik-routeros-actively-exploited/
• https://cert.pl/en/posts/2026/09/mikrotik-routeros-cve
• https://npratley.net/reversing-mikrotiks-silent-patch-the-routeros-7-23-4-fix-they-wouldnt-explain/
• https://forum.mikrotik.com/t/6-49-21-long-term-is-released/272802
• https://forum.mikrotik.com/t/7-23-4-long-term-is-released/272801
• https://forum.mikrotik.com/t/7-24-2-stable-is-released/272800
• https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-86060