# CVE-2026-109357: LibreNMS before 26.9.0 LDAP Filter Injection Authentication Bypass via Authorization Header

> Unauthenticated attackers can gain admin access via LDAP filter injection in LibreNMS when using specific authorization modes without REMOTE_USER forwarding.

- **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:** 12 Oct 2026
- **Updated:** 15 Oct 2026
- **Also known as:** GHSA-7cmx-65c5-8h8v, GHSA-rx4g-rhf6-xw5x

## What is CVE-2026-109357?

CVE-2026-109357 is a critical authentication bypass vulnerability in librenms, published on 12 Oct 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

LibreNMS before 26.9.0 contains an LDAP filter injection in ldap-authorization and ad-authorization modes because usernames are inserted unescaped into LDAP search filters and authentication only checks user existence. When REMOTE_USER is not forwarded, unauthenticated attackers can send a wildcard username via HTTP Basic Authorization (PHP_AUTH_USER) to match all users and groups and gain admin access.

Weakness: CWE-90 (Improper Neutralization of Special Elements used in an LDAP Query)

## Which versions are affected by CVE-2026-109357?


## How do I fix CVE-2026-109357?

No fix has been published for CVE-2026-109357 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-109357 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-109357 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-109357 and fix it if it is affected.

What it is: CVE-2026-109357 is a critical authentication bypass vulnerability in librenms, published on 12 Oct 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-2026-109357 exists.

Affected product: 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-2026-109357/ (Markdown: https://insights.sbomify.com/CVE-2026-109357/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-109357
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-109357
- OSV: https://osv.dev/vulnerability/CVE-2026-109357

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-109357/
Summaries are generated and may contain mistakes; the official description above is the record.