# CVE-2026-54088: File Browser: Command Injection via Authentication Hook Shell Substitution (Pre-Authentication RCE)

> Unauthenticated attackers can execute arbitrary OS commands via shell metacharacters in login credentials when the authentication hook feature is enabled.

- **Severity:** Critical 9.3 (`CVSS:4.0/AV:N/AC:L/AT:N/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:** Yes
- **Published:** 25 Jun 2026
- **Updated:** 25 Jun 2026
- **Also known as:** GHSA-m93h-4hw7-5qcm, GO-2026-5962

## What is CVE-2026-54088?

CVE-2026-54088 is a critical command injection 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. Prior to 2.63.6, the Hook Authentication feature in File Browser allows administrators to delegate login verification to an external shell command. User-supplied credentials (username and password) are interpolated into this command string using os.Expand without sanitization. An unauthenticated remote attacker can inject shell metacharacters in the username or password field at the login screen, causing the server to execute arbitrary OS commands before any authentication takes place. This is a critical pre-authentication RCE. This vulnerability is fixed in 2.63.6.

Weakness: CWE-88 (Improper Neutralization of Argument Delimiters in a Command), CWE-78 (Improper Neutralization of Special Elements used in an OS Command), CWE-306 (Missing Authentication for Critical Functionality)

## Which versions are affected by CVE-2026-54088?

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 | All versions | 2.63.6 |
| `github.com/filebrowser/filebrowser/v2` | Go | All versions | 2.63.6 |
| `github.com/filebrowser/filebrowser/v2` | Go | All versions | 2.63.6 |
| `github.com/filebrowser/filebrowser` | Go | All versions | None |

## How do I fix CVE-2026-54088?

Upgrade github.com/filebrowser/filebrowser/v2 to 2.63.6 or later.

## Is CVE-2026-54088 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-54088 exists.

Public exploit code:

- https://github.com/Saku0512/CVE-2026-54088-poc (github_poc): https://github.com/Saku0512/CVE-2026-54088-poc

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-54088 and fix it if it is affected.

What it is: CVE-2026-54088 is a critical command injection 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-2026-54088 exists.

Affected packages and fixed versions:
- github.com/filebrowser/filebrowser/v2 (Go): affected all versions; fixed in 2.63.6
- github.com/filebrowser/filebrowser/v2 (Go): affected all versions; fixed in 2.63.6
- github.com/filebrowser/filebrowser/v2 (Go): affected all versions; fixed in 2.63.6
- 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-2026-54088/ (Markdown: https://insights.sbomify.com/CVE-2026-54088/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-54088
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-54088
- OSV: https://osv.dev/vulnerability/CVE-2026-54088

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From sbomify Insights: https://insights.sbomify.com/CVE-2026-54088/
Summaries are generated and may contain mistakes; the official description above is the record.