CVE-2026-103903
CVSS v3
8.8
HIGH
EPSS Score
—
exploit probability
CISA KEV
No
known exploited
Exploitation
—
SSVC status
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Affected and fixed versions
Neither OSV.dev nor the vendor advisories we read list affected versions for CVE-2026-103903 yet.
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.
Technical details
- CVSS v3 Vector
- CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
- Published
- 2026-10-12
- Last Modified
- 2026-10-12
Frequently asked questions
What is CVE-2026-103903?
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.
Is CVE-2026-103903 actively exploited?
Active exploitation of CVE-2026-103903 has not been confirmed.
What is the CVSS score for CVE-2026-103903?
CVE-2026-103903 has a CVSS v3 base score of 8.8 (HIGH severity), with vector string CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H.
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