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CVE-2026-103903

8.8 · HIGH

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…

Published Oct 12, 2026CWE-863EPSS 0.41%

Overview

CVE-2026-103903 is a high-severity vulnerability. It was published on October 12, 2026 and has a CVSS 3.1 base score of 8.8 (HIGH).

This vulnerability has a CVSS 3.1 base score of 8.8, rated HIGH. It can be exploited remotely over the network. Some level of privileges is required for exploitation.

Technical 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.

Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

References

Refbr2sec.com/lv/resursi/2026-routeros-winbox-auth-bypass/Refcvd.cert.lv/disclosed/vuln-all-709639748Refforum.mikrotik.com/t/7-25rc1-testing-is-released/27352Refmikrotik.com/download/changelogs?channelFilter=stable&versionFilter=7.24.5

How CyberStrike helps

Frequently asked questions

What is CVE-2026-103903?

CVE-2026-103903 is a high-severity vulnerability. It was published on October 12, 2026 and has a CVSS 3.1 base score of 8.8 (HIGH).

How severe is CVE-2026-103903?

This vulnerability has a CVSS 3.1 base score of 8.8, rated HIGH. It can be exploited remotely over the network. Some level of privileges is required for exploitation.

How do I fix or remediate CVE-2026-103903?

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

How can CyberStrike help with CVE-2026-103903?

CyberStrike is an open-source, AI-augmented pentesting engine. Rather than flag a version number, it tests whether an issue like CVE-2026-103903 is actually reachable in your own applications and APIs, then verifies each finding before reporting it. That tells you if the weakness is a real, exploitable risk in your environment or a false positive you can safely deprioritize.

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