Auth bypass in Librenms
CVE-2026-86426
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.
Vulnerability class: Broken Authentication
Published · last modified .
CVSS v3 metric
CVSS v3 base score 9.8 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.
EPSS exploit prediction
EPSS: 0.039 (90.1th percentile), scored .
Low probability of exploitation in the next 30 days, but still tracked. 90th percentile — 90.1% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.021 · newest: 0.039 · change: +0.018
Affected products
Weakness classification (CWE)
References
- github.com/librenms/librenms/security/advisories/GHSA-cvq8-gqfq-3mvg (Exploit, vendor-advisory, Vendor Advisory)
- www.vulncheck.com/advisories/librenms-before-26.8.0-authentication-bypass-via-a… (Third Party Advisory, third-party-advisory)
Frequently asked questions
- What is CVE-2026-86426?
- CVE-2026-86426 is a critical-severity vulnerability in Librenms, classified under Improper Authentication. CVSS score: 9.8/10. Published 2026-09-07.
- How severe is CVE-2026-86426?
- Critical severity. CVSS v3 base score is 9.8 out of 10.