What’s Vulnerable › Vulnerabilities

CVE-2026-103903: MikroTik RouterOS WinBox split-principal authentication bypass allows privilege escalation

• Severity: high (CVSS 8.8 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.4% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-10-12 · updated 2026-10-16
• Weakness: CWE-863

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.

Affected products

• MikroTik RouterOS: from 7.0.0 before 7.24.5 — fixed in 7.24.5

How to fix

Upgrade to a fixed version: MikroTik RouterOS 7.24.5. Check the vendor advisory for mitigations.

References

• https://br2sec.com/lv/resursi/2026-routeros-winbox-auth-bypass/
• https://cvd.cert.lv/disclosed/vuln-all-709639748
• https://forum.mikrotik.com/t/7-25rc1-testing-is-released/27352
• https://mikrotik.com/download/changelogs?channelFilter=stable&versionFilter=7.24.5

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