EUVD-2026-20896CVSS Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:N
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3Description
OPNsense is a FreeBSD based firewall and routing platform. Prior to 26.1.6, OPNsense's LDAP authentication connector passes the login username directly into an LDAP search filter without calling ldap_escape(). An unauthenticated attacker can inject LDAP filter metacharacters into the username field of the WebGUI login page to enumerate valid LDAP usernames in the configured directory. When the LDAP server configuration includes an Extended Query to restrict login to members of a specific group, the same injection can be used to bypass that group membership restriction and authenticate as any LDAP user whose password is known, regardless of group membership. This vulnerability is fixed in 26.1.6.
Analysis
LDAP filter injection in OPNsense firewall allows unauthenticated attackers to enumerate valid LDAP usernames and bypass group membership restrictions via the WebGUI login page. Affects OPNsense versions prior to 26.1.6. …
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Remediation
Within 24 hours: Immediately inventory all OPNsense deployments and identify any running versions prior to 26.1.6; implement network segmentation to restrict WebGUI access to trusted administrative networks only. Within 7 days: Contact OPNsense support to confirm availability of version 26.1.6 or later patched release; test patch in non-production environment. …
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