CVE-2026-103903 MikroTik RouterOS - Authentication Bypass

MikroTik RouterOS contains an incorrect authorization vulnerability in the WinBox authentication flow, letting remote authenticated low-privilege users escalate to full administrative privileges by specifying a higher-privilege account, exploit requires valid low-privilege credentials.

CVSS base score 8.8 /10
High
CISA KEV
Not listed
Public exploit
None known
Authentication
Required
EPSS
0.41% chance of exploitation in 30 days
View the NVD record ↗

Details

Type
Authentication Bypass
Impact
Privilege Escalation
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Published
12 October 2026
Updated
15 October 2026
Weakness
CWE-863

Vendor fix

Update to the latest MikroTik RouterOS version with the WinBox authentication fix.

Patching closes this CVE. It does not tell you which of your systems run the affected version, or what else is exposed alongside them.

References

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