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Vulnerability record · CVE-2026-86426 · published 7 September 2026

CVE-2026-86426: Librenms improper authentication vulnerability

Librenms · Librenms

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.

9.2 CVSS 4.0 Critical EPSS 3.9% · top 10.2% CWE-287 · Improper authentication
9.2CVSS 4.0 base score
3.9%EPSS exploitation probability, 30 days
NoNot in CISA KEV
1Affected product versions listed by NVD
3References, 2 tagged exploit
18 Sep 2026Last modified by NVD

Description

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.

CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:

Affected products

1 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://github.com/librenms/librenms/security/advisories/GHSA-cvq8-gqfq-3mvg ExploitVendor Advisory
https://www.vulncheck.com/advisories/librenms-before-26.8.0-authentication-bypass-via-api-token-type-confusion Third Party Advisory
https://github.com/librenms/librenms/security/advisories/GHSA-cvq8-gqfq-3mvg ExploitVendor Advisory

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Related vulnerabilities

Same products first, then exploited flaws of the same weakness class.

9.8CVE-2022-4070Librenms insufficient session expiration vulnerabilityInsufficient Session Expiration in GitHub repository librenms/librenms prior to 22.10.0.EPSS 0.65%9.8CVE-2022-29712Librenms command injection vulnerabilityLibreNMS v22.3.0 was discovered to contain multiple command injection vulnerabilities via the service_ip, hostname, and service_param parameters.EPSS 1.7%9.8CVE-2021-44278Librenms path traversal vulnerabilityLibrenms 21.11.0 is affected by a path manipulation vulnerability in includes/html/pages/device/showconfig.inc.php.EPSS 1.5%9.8CVE-2019-10665Librenms injection vulnerabilityAn issue was discovered in LibreNMS through 1.47. The scripts that handle the graphing options (html/includes/graphs/common.inc.php and html/includes…EPSS 1.5%9.8CVE-2018-20434LibreNMS addhost OS command injection via community parameterLibreNMS 1.46 fails to sanitize the $_POST['community'] parameter in html/pages/addhost.inc.php when creating a new device, and the value is later mi…EPSS 71%analysed9.3CVE-2026-26988Librenms sql injection vulnerabilityLibreNMS is an auto-discovering PHP/MySQL/SNMP based network monitoring tool. Versions 25.12.0 and below contain an SQL Injection vulnerability in th…EPSS 0.48%9.1CVE-2024-51092Librenms os command injection vulnerabilityLibreNMS before 24.10.0 allows a remote attacker to execute arbitrary code via OS command injection involving AboutController.php's index(), Settings…EPSS 7.2%9.1CVE-2019-10668Librenms missing authentication for critical function vulnerabilityAn issue was discovered in LibreNMS through 1.47. A number of scripts import the Authentication libraries, but do not enforce an actual authenticatio…EPSS 1.6%

Source: NIST National Vulnerability Database (record CVE-2026-86426), CISA KEV, FIRST EPSS (scores of 2026-09-26). This page is refreshed as NVD updates the record.