CVE-2026-34578: OPNsense is a FreeBSD based firewall and routing platform

Q: How do I fix CVE-2026-34578?

opnsense: upgrade to 26.1.6. Exact commands for each OS are on this page.

Q: Is CVE-2026-34578 being exploited?

CVE-2026-34578 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2026-34578 affect?

CVE-2026-34578 affects opnsense. Severity is high (CVSS 8.2). 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 ca

Q: How urgent is CVE-2026-34578?

Priority 48/100. High severity; Public exploit reference; Remotely exploitable, no login, no user action

This week

HIGH 8.2REMOTEUPGRADE

CVE-2026-34578 is a high-severity flaw (CVSS 8.2) affecting opnsense. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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

Why this priority

High severity
Public exploit reference
Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	8.2 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	0.4% (top 64%)
CISA exploited list	No
Weakness	CWE-90
Published	2026-04-09
Last modified	2026-10-26

Publisher (CNA): GitHub, Inc. · Vendor: opnsense

Last updated 2026-10-26 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-04-09 15:16 UTCPublished CVE record published
2026-10-26 22:10 UTCUpdated Record last modified

opnsense opnsense UPGRADE

Affected: < 26.1.6

Fixed in: 26.1.6

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy opnsense || rpm -q opnsense || opnsense --version

2. UPGRADE to 26.1.6 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade opnsense

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade opnsense

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2026-34578?

opnsense: upgrade to 26.1.6. Exact commands for each OS are on this page.

Is CVE-2026-34578 being exploited?

CVE-2026-34578 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2026-34578 affect?

CVE-2026-34578 affects opnsense. Severity is high (CVSS 8.2). 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 ca

How urgent is CVE-2026-34578?

Priority 48/100. High severity; Public exploit reference; Remotely exploitable, no login, no user action

Software pages

pfSense and OPNsense vulnerabilities

Related CVEs

CVE-2026-44194 CRITICAL 9.1 UPGRADE OPNsense is a FreeBSD based firewall and routing platform
CVE-2026-44193 CRITICAL 9.1 UPGRADE OPNsense is a FreeBSD based firewall and routing platform
CVE-2026-45158 CRITICAL 9.1 UPGRADE OPNsense is a FreeBSD based firewall and routing platform
CVE-2026-44195 MEDIUM 5.3 UPGRADE OPNsense is a FreeBSD based firewall and routing platform

References

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