CVE-2026-34578 OPNsense has an LDAP Injection via Unsanitized Username in Authentication
Unauthenticated attackers can inject LDAP filters to enumerate users or bypass group restrictions in OPNsense firewall authentication.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-34578?
CVE-2026-34578 is a high-severity vulnerability in opnsense core, published on 9 Apr 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
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.
Weakness: CWE-90
Which versions are affected by CVE-2026-34578?
It affects 1 product.
Products include Opnsense Opnsense.
How do I fix CVE-2026-34578?
No fix has been published for CVE-2026-34578 yet. Limit exposure of the affected software until one is available.
Is CVE-2026-34578 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-34578 exists.
Other vulnerabilities in opnsense core
Sources
Also known as GHSA-jpm7-f59c-mp54.