Vulnerability · Published Sep 7, 2026 · Assigned by VulnCheck

CVE-2026-86426LibreNMS before 26.8.0 Authentication Bypass via API Token Type Confusion

Critical 9.2

In plain English

A critical-severity improper authentication in librenms from librenms. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 4.4% (higher than 91% of all known vulnerabilities). Ready-made attack tooling exists: Nuclei, public proof-of-concept code.

Severity (CVSS 4.0)9.2Critical

Exploit odds (30 days)4.4%top 8.7% of all CVEs

Exploited in the wildNo reportsCISA SSVC: poc

Attack tooling2Nuclei, Public PoC

Official 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.

Affected products (as reported)

Vendor	Product	Versions
librenms	librenms	0 – before 26.8.0

Weakness: CWE-287 · Vector: 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

References

GitHub Security Advisory (GHSA-cvq8-gqfq-3mvg) vendor-advisory
VulnCheck Advisory: LibreNMS before 26.8.0 Authentication Bypass via API Token Type Confusion third-party-advisory