CVE-2026-86426: librenms vulnerability

What is known

LibreNMS before 26.8.0 contains an authentication bypass vulnerability in the REST API that allows unauthenticated attackers to access protected endpoints by sending numeric values instead of string tokens. Attackers can exploit MySQL type coercion by sending small integers like 0 through 9 to match token hashes, gaining access to API functionality including device credentials and administrative features that enable remote code execution through alert templates.

Business impact

Successful exploitation of CVE-2026-86426, a critical vulnerability (CVSS 9.2) affecting librenms, may affect the confidentiality, integrity or availability of the vulnerable environment. The exact impact depends on the installed version, exposed interfaces and deployment configuration.

Recommended administrator action

Confirm whether librenms is present and compare installed versions with the vendor advisory and NVD record. Apply the vendor patch or documented mitigation; until remediation is complete, reduce exposure of affected interfaces, review relevant logs and monitor for indicators of exploitation. DataHouse can support version verification, managed patching, network exposure reduction, log review and backup validation for dedicated, cloud and colocated environments.

Sources

• NVD
• Reference
• Reference