CyberSecBulletin
CVE-2026-34578NVD status: Analyzed

core: Improper Neutralization of Special Elements used in an LDAP Query

Published Updated By the CyberSecBulletin desk

CVE-2026-34578 is a high-severity improper neutralization of special elements used in an LDAP query vulnerability in core from Opnsense, with a CVSS 3.1 base score of 8.2 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. Affected core versions: < 26.1.6. The record does not name a fixed version, so check the vendor advisory. There is no confirmed exploitation so far. EPSS estimates a 0.42% chance of exploitation within 30 days, which is low compared with other CVEs.

Next patch cycle

High severity with no evidence of exploitation so far.

What to do

  1. Update Opnsense to 26.1.6 or a later version.
  2. Read the advisory on github.com for workarounds and exact fixed builds.
  3. Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.

Affected products and versions

VendorProductAffected versionsFixed in
Opnsensecore< 26.1.6Not stated
OpnsenseOpnsensebefore 26.1.626.1.6

Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.

How the severity score breaks down

Attack vector
NetworkCan be exploited remotely over a network, including the internet.
Attack complexity
LowNo special conditions are needed; the attack works reliably.
Privileges required
NoneNo account or login is needed.
User interaction
NoneNo action by a victim is required.
Scope
UnchangedImpact stays within the vulnerable component.
Confidentiality
HighAll data handled by the component can be read.
Integrity
LowLimited modification of data is possible.
Availability
NoneAvailability is not affected.

Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:N. Scored by CNA (github.com).

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.

Source: the CVE record as published by its numbering authority, via NVD and CVE.org.

The underlying weakness: Improper Neutralization of Special Elements used in an LDAP Query

The product constructs all or part of an LDAP query using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the intended LDAP query when it is sent to a downstream component.

More Improper Neutralization of Special Elements used in an LDAP Query vulnerabilities (CWE-90)

Timeline

  1. CVE record published.
  2. CISA published its SSVC assessment (exploitation: poc, automatable: yes, technical impact: partial).
  3. Record last changed materially (score, affected products, status or references).

References

Other vulnerabilities in core

All core vulnerabilities

Recent Improper Neutralization of Special Elements used in an LDAP Query vulnerabilities

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