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

> Unauthenticated attackers can bypass API authentication via type confusion to access credentials and execute remote code through alert templates.

- **Severity:** Critical 9.2 (`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`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 7 Sep 2026
- **Updated:** 8 Sep 2026
- **Also known as:** GHSA-84cr-xjpw-q9mc, GHSA-cvq8-gqfq-3mvg

## What is CVE-2026-86426?

CVE-2026-86426 is a critical authentication bypass vulnerability in Librenms Librenms, published on 7 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### 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.

Weakness: CWE-287 (Improper Authentication)

## Which versions are affected by CVE-2026-86426?

It affects 1 product.


Products: Librenms Librenms.

## How do I fix CVE-2026-86426?

No fix has been published for CVE-2026-86426 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-86426 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-86426 exists.

Public exploit code:

- CVE-2026-86426 CHECK (github_poc): https://github.com/Guila95/CVE-2026-86426
- LibreNMS <= 26.7.0 - Unauthenticated API Access (nuclei): http/cves/2026/CVE-2026-86426.yaml

## Other vulnerabilities in Librenms Librenms

- [CVE-2023-4982](https://insights.sbomify.com/CVE-2023-4982/): Cross-site Scripting (XSS) - Stored in librenms/librenms (critical 9.8)
- [CVE-2022-29712](https://insights.sbomify.com/CVE-2022-29712/): Command injection in librenms (critical 9.8)
- [CVE-2021-44278](https://insights.sbomify.com/CVE-2021-44278/): Path traversal in librenms/librenms (critical 9.8)
- [CVE-2019-10665](https://insights.sbomify.com/CVE-2019-10665/): LibreNMS Information Disclosure (critical 9.8)
- [CVE-2018-20434](https://insights.sbomify.com/CVE-2018-20434/): LibreNMS arbitrary OS commands execution (critical 9.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-86426 and fix it if it is affected.

What it is: CVE-2026-86426 is a critical authentication bypass vulnerability in Librenms Librenms, published on 7 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-86426 exists.

Affected product: Librenms Librenms. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-86426/ (Markdown: https://insights.sbomify.com/CVE-2026-86426/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-86426
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-86426
- OSV: https://osv.dev/vulnerability/CVE-2026-86426

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-86426/
Summaries are generated and may contain mistakes; the official description above is the record.