# CVE-2026-54089: File Browser: Authentication Bypass via Proxy Auth Header Forgery

> Attackers can bypass authentication and create accounts by forging proxy headers when proxy authentication is enabled.

- **Severity:** Critical 9.1 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 25 Jun 2026
- **Updated:** 25 Jun 2026
- **Also known as:** GHSA-xqp3-jq6g-x3qm, GO-2026-5966

## What is CVE-2026-54089?

CVE-2026-54089 is a critical authentication bypass vulnerability in filebrowser, published on 25 Jun 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

File Browser is a file managing interface for uploading, deleting, previewing, renaming, and editing files within a specified directory. Starting with 2.0.0-rc.1, when FileBrowser is configured with proxy authentication (auth.method=proxy), any unauthenticated attacker who can reach the server directly can impersonate any user - including admin - by sending a single forged HTTP header. No credentials are required. Additionally, specifying a non-existent username causes the server to automatically create a new user account, providing an account creation primitive with no authorization. This is an already known issue that has been documented in the documentation for several years, but has not been documented as a vulnerability before.

Weakness: CWE-290 (Authentication Bypass by Spoofing), CWE-287 (Improper Authentication)

## Which versions are affected by CVE-2026-54089?

4 open source packages ship an affected version, including github.com/filebrowser/filebrowser/v2 and github.com/filebrowser/filebrowser.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `github.com/filebrowser/filebrowser/v2` | Go | From 2.0.0-rc.1 | None |
| `github.com/filebrowser/filebrowser/v2` | Go | From 2.0.0-rc.1 to 2.63.18 | None |
| `github.com/filebrowser/filebrowser/v2` | Go | From 2.0.0-rc.1 to 2.63.18 | None |
| `github.com/filebrowser/filebrowser` | Go | All versions | None |

## How do I fix CVE-2026-54089?

Change a configuration setting.

## Is CVE-2026-54089 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-54089 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-54089 and fix it if it is affected.

What it is: CVE-2026-54089 is a critical authentication bypass vulnerability in filebrowser, published on 25 Jun 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-2026-54089 exists.

Affected packages and fixed versions:
- github.com/filebrowser/filebrowser/v2 (Go): affected from 2.0.0-rc.1; no fix listed
- github.com/filebrowser/filebrowser/v2 (Go): affected from 2.0.0-rc.1 up to 2.63.18; no fix listed
- github.com/filebrowser/filebrowser/v2 (Go): affected from 2.0.0-rc.1 up to 2.63.18; no fix listed
- github.com/filebrowser/filebrowser (Go): affected all versions; no fix listed

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-2026-54089/ (Markdown: https://insights.sbomify.com/CVE-2026-54089/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-54089
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-54089
- OSV: https://osv.dev/vulnerability/CVE-2026-54089

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-54089/
Summaries are generated and may contain mistakes; the official description above is the record.