CVE-2026-109357 (CVSS 8.1)

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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CVSS v3.1 Score

8.1

HIGH

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H

EPSS — Exploit Prediction

0.0046

Probability of exploitation

0.38%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-90 CWE-90

References

Other References

https://github.com/librenms/librenms/security/advisories/GHSA-7cmx-65c5-8h8v https://www.vulncheck.com/advisories/librenms-before-26.9.0-ldap-filter-injection-authentication-bypass-via-authorization-header https://github.com/librenms/librenms/security/advisories/GHSA-7cmx-65c5-8h8v

Frequently Asked Questions

What is CVE-2026-109357? +

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. It has a CVSS v3.1 base score of 8.1 (HIGH).

How severe is CVE-2026-109357? +

CVE-2026-109357 has a CVSS v3.1 score of 8.1 out of 10, rated HIGH. This is a high-severity vulnerability that should be prioritized for patching. The EPSS score is 0.0046, placing it in the 0th percentile for exploitation probability.

How do I check if I'm vulnerable to CVE-2026-109357? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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CVE-2026-109357