CVE-2026-103903 json
MikroTik RouterOS WinBox split-principal authentication bypass allows privilege escalation
published 28d ago modified 24d ago also EUVD-2026-97325
- cvss
- 8.8
- version 3.1, CNA
- cisa kev
- Not listed
- not in CISA's catalog
- epss
- 0.4%
- EPSS 0.4% chance of exploitation in 30 days, percentile 36%
- public exploits
- 0
- none known
Summary
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.
Patch / fix
- MikroTik RouterOS 7.24.5, 7.25rc1
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Check with FencerCISA SSVC
- Exploitation
- none
- Automatable
- no
- Technical impact
- total
- Assessed
- 27d ago
Exploit prediction
0.42% chance of exploitation in the next 30 days, higher than 36% of all scored CVEs (FIRST EPSS, 2026-11-09).
CVSS scores
| assigned by | version | score | vector |
|---|---|---|---|
| CNA | 4.0 | 8.7 | CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N |
| CNA | 3.1 | 8.8 | CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H |
| CNA | 4.0 | 8.7 | CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X |
Affected products
- MikroTik RouterOS
Classification
- Weakness
-
- CWE-863 Incorrect Authorization
References
-
mikrotik.com
/download/changelogs?channelFilter=stable&versionFilter=7.24.5
release-notes
-
forum.mikrotik.com
/t/7-25rc1-testing-is-released/27352
release-notes
-
br2sec.com
/lv/resursi/2026-routeros-winbox-auth-bypass/
technical-description, third-party-advisory
-
cvd.cert.lv
/disclosed/vuln-all-709639748
government-resource
Sources
- CVE List CVE-2026-103903
- NVD CVE-2026-103903
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