CVE-2026-103903
Received Received - Intake

Incorrect Authorization in MikroTik RouterOS WinBox Authentication

Publication date: 2026-10-12

Last updated on: 2026-10-12

Assigner: ENISA

Description
An incorrect authorization vulnerability in the WinBox authentication flow of MikroTik RouterOS allows a remote authenticated attacker with credentials for a low-privilege account permitted to use WinBox to obtain the authorization policy of a different existing account. The stage-one EC-SRP challenge and proof are verified using the attacker's account, while the independently supplied stage-two username is used to install the target account's privileges. By specifying a higher-privilege account such as admin, a low-privilege user can obtain a full administrative session without knowing the target account's password and can use that session to increase the privileges of the attacker's own account.

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Meta Information

Published
2026-10-12
Last Modified
2026-10-12
Generated
2026-10-12
AI Q&A
2026-10-12
EPSS Evaluated
N/A
NVD
CVE-2026-103903
EUVD
EUVD-2026-97325

Affected Vendors & Products

Showing 1 associated CPE
Vendor Product Version / Range
MikroTik RouterOS 7.0.0

Helpful Resources

Exploitability

CWE
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KEV
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CWE ID Description
CWE-863 The product performs an authorization check when an actor attempts to access a resource or perform an action, but it does not correctly perform the check.

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Executive Summary

This vulnerability is an incorrect authorization flaw in MikroTik RouterOS's WinBox authentication flow. A remote attacker with low-privilege credentials can exploit it to gain full administrative access to the device. The issue occurs because the system fails to properly bind the authentication stages, allowing the attacker to use their own credentials in the first stage while specifying a higher-privilege account like 'admin' in the second stage. This grants unauthorized access without needing the admin password.

Detection Guidance

This vulnerability can be detected by checking the RouterOS version on MikroTik devices. If the version is prior to 7.24.4, the device is vulnerable. Use the command /system package print in the RouterOS CLI to check the installed version.

Impact Analysis

This vulnerability allows an attacker to take full control of your MikroTik RouterOS device. They can export backups, modify firewall rules, load custom packages, and make unauthorized changes to your network configuration. Since it doesn't require password brute-forcing, it can be exploited quickly and silently, leading to potential data breaches or network disruptions.

Compliance Impact

This vulnerability could lead to non-compliance with GDPR, HIPAA, and other regulations due to unauthorized access and potential data breaches. If an attacker gains administrative access, they may exfiltrate sensitive data, modify security settings, or disrupt critical services, violating confidentiality and integrity requirements of these standards.

Mitigation Strategies

Immediately update RouterOS to version 7.24.5 (stable) or 7.25rc1 (testing) or later. This can be done via the RouterOS package updater or by manually downloading the update from MikroTik's official website.

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