Vulnerability · Published Apr 9, 2026 · Assigned by GitHub_M

CVE-2026-34578OPNsense has an LDAP Injection via Unsanitized Username in Authentication

High 8.2

In plain English

A high-severity security flaw in core from opnsense. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.4% (higher than 37% of all known vulnerabilities).

Severity (CVSS 3.1)8.2High

Exploit odds (30 days)0.4%top 63.2% of all CVEs

Exploited in the wildNo reportsCISA SSVC: poc

Attack toolingNoneno public tooling known

Official 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.

Affected products (as reported)

Vendor	Product	Versions
opnsense	core	< 26.1.6

Weakness: CWE-90 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:N

References

https://github.com/opnsense/core/security/advisories/GHSA-jpm7-f59c-mp54 x_refsource_CONFIRM
https://github.com/opnsense/core/commit/016f66cb4620cd48183fa97843f343bb71813c6e x_refsource_MISC