CVE-2026-103903MikroTik RouterOS WinBox split-principal authentication bypass allows privilege escalation
Updated under an hour ago ()
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It affects MikroTik RouterOS. Add what you run to find out whether that includes you.
EPSS puts the chance of exploitation in the next 30 days at 0.41%, higher than 34% of scored CVEs.
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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.
- CVSS
- 8.8 HIGH (v3.1, CNA)CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
- Weakness (CWE)
- CWE-863
- Known exploited
- Not in CISA's KEV catalog
- EPSS (exploitation in the next 30 days)
- 0.41% (percentile 34)
- Assigned by
- ENISA
- NVD analysis
- Awaiting Analysis
- Record last updated
- Oct 13, 2026
- First seen by InfoSec Signals
- Oct 12, 2026
Affected products
MikroTik RouterOS mikrotik:routeros (from the name) | from 7.0.0 before 7.24.5; 7.25rc1 not affected | CNA record |
References
- https://mikrotik.com/download/changelogs?channelFilter=stable&versionFilter=7.24.5release-notes
- https://forum.mikrotik.com/t/7-25rc1-testing-is-released/27352release-notes
- https://br2sec.com/lv/resursi/2026-routeros-winbox-auth-bypass/technical-description, third-party-advisory
- https://cvd.cert.lv/disclosed/vuln-all-709639748government-resource
The CVE record on cve.org NVD's entry
The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.