CVE-2026-109357
Received Received - Intake

LDAP Filter Injection in LibreNMS Before 26.9.0

Publication date: 2026-10-12

Last updated on: 2026-10-12

Assigner: VulnCheck

Description
LibreNMS before 26.9.0 contains an LDAP filter injection in ldap-authorization and ad-authorization modes because usernames are inserted unescaped into LDAP search filters and authentication only checks user existence. When REMOTE_USER is not forwarded, unauthenticated attackers can send a wildcard username via HTTP Basic Authorization (PHP_AUTH_USER) to match all users and groups and gain admin access.

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Meta Information

Published
2026-10-12
Last Modified
2026-10-12
Generated
2026-10-12
AI Q&A
2026-10-12
EPSS Evaluated
N/A
NVD
CVE-2026-109357
EUVD
EUVD-2026-97659

Affected Vendors & Products

Showing 1 associated CPE
Vendor Product Version / Range
librenms librenms 0

Helpful Resources

Exploitability

CWE
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KEV
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CWE ID Description
CWE-90 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.

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Executive Summary

LibreNMS before version 26.9.0 has an LDAP filter injection vulnerability in its ldap-authorization and ad-authorization modes. The issue occurs because usernames are inserted directly into LDAP search filters without proper escaping. This allows unauthenticated attackers to exploit it by sending a wildcard username via HTTP Basic Authorization (PHP_AUTH_USER) when REMOTE_USER is not forwarded.

Detection Guidance

Check LibreNMS version with 'php -r "include \"includes\/defs.php\"; echo $config['version'];". If version is below 26.9.0, the system is vulnerable.

Impact Analysis

An attacker could gain unauthorized admin access by matching all users and groups in the LDAP directory. This could lead to full system compromise, data breaches, or unauthorized changes to network monitoring configurations.

Compliance Impact

This vulnerability could lead to unauthorized access to sensitive data, violating GDPR's data protection requirements and HIPAA's security rules. Organizations using affected LibreNMS versions may face compliance violations, legal penalties, and reputational damage.

Mitigation Strategies

Upgrade LibreNMS to version 26.9.0 or later immediately. If immediate upgrade is not possible, disable LDAP/AD authorization modes as a temporary workaround.

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