CVE-2026-86426

LibreNMS before 26.8.0 Authentication Bypass via API Token Type Confusion

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.

Affected

librenms

CVSS v4.0 VULNCHECK

9.2 CRITICALCVSS: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:X/V:X/RE:X/U:X

CVSS v3.1 NVD

9.8 CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

EPSS

3.87% chance of exploitation in the next 30 days, 90th percentile

Nuclei

critical · CWE-287

Published

2026-09-07

Updated

2026-09-08

Nuclei templates (1)

• projectdiscovery/nuclei-templates/blob/main/http/cves/2026/CVE-2026-86426.yaml

Security advisories

• librenms/librenms/security/advisories/GHSA-cvq8-gqfq-3mvg
• https://www.vulncheck.com/advisories/librenms-before-26.8.0-authentication-bypass-via-api…

References

• CVE Record
• NVD entry