Secuno
ENNL
Book demo

CVE-2026-34578

Opnsense vulnerability

8.2 HIGHPublic exploitEPSS 0.48%
  1. Published9 Apr 2026

Description

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.

CVSS 3.1 breakdown

Attack vectorNetwork
Attack complexityLow
Privileges requiredNone
User interactionNone
ScopeUnchanged
ConfidentialityHigh
IntegrityLow
AvailabilityNone
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:N

Affected products

Opnsense< 26.1.6

Remediation

Fixed in
Opnsense≥ 26.1.6

References

Related CVEs

Recent high-severity vulnerabilities sharing a weakness type.

CVE-2026-1093578.1
LibreNMS before 26.9.0 contains an LDAP filter injection in ldap-authorization and…
CVE-2026-940539.1
Authentication bypass via LDAP injection in component sshd-ldap in Apache MINA SSHD…
CVE-2026-750208.1
Improper Neutralization of Special Elements used in an LDAP Query ('LDAP Injection')…
CVE-2026-582228.8
A security flaw combining LDAP filter injection and improper authorization checks was…
CVE-2026-473038.8
Authentication bypass by assumed-immutable data in ASP.NET Core allows an authorized…
CVE-2026-42568.2
Improper neutralization of special elements used in an LDAP query ('LDAP injection')…

Frequently asked

Is CVE-2026-34578 being actively exploited?

CVE-2026-34578 is not in the CISA KEV catalog. A public exploit reference exists, so treat it as exploitable. Its EPSS exploit probability is 0.48%.

How severe is CVE-2026-34578?

CVE-2026-34578 has a CVSS 3.1 base score of 8.2, rated high. EPSS estimates a 0.48% probability of exploitation.

Which products are affected by CVE-2026-34578?

Affected products include Opnsense.

How do I fix CVE-2026-34578?

Upgrade affected software to a fixed version, for example Opnsense 26.1.6 or later, then confirm no affected versions remain in your inventory.

How Secuno handles this

Secuno correlates vulnerabilities like CVE-2026-34578 against the real software inventory on every managed device, every day. Rather than a static severity, each match is scored in context: exploit availability, EPSS, the asset's exposure, and business criticality decide where it lands in the queue. If an affected version is present anywhere across your portfolio, it surfaces automatically with a prioritised remediation path.

See how prioritisation worksBook a demo

Get Patch this first every Monday

Five vulnerabilities that matter this week, ranked on real exploitation. Plain language, one email, no spam.

You can unsubscribe with one click from every issue. We handle your details as described in our privacy policy.

Data from the NVD, CISA KEV catalog and FIRST EPSS. CVSS 3.1 base score shown where available.