File Browser has a Command Execution Allowlist Bypass via Shell Metacharacter Injection

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS 4.0

8.7 · CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N · score source

EPSS

• CVE-2026-54090: 0.44% estimated exploitation activity in the next 30 days; percentile 38.04 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

[!NOTE] This feature has been disabled by default for all installations from v2.33.8 onwards, including for existent installations. To exploit this vulnerability, the instance administrator must turn on a feature and ignore all the warnings about known vulnerabilities. We're publishing this new advisory to make it clear that all vulnerabilities concerning this feature are disclosed. For more information about tracking vulnerability issues related to the Command Execution features, check https://github.com/filebrowser/filebrowser/issues/5199. Summary When a shell interpreter is configured (e.g. /bin/sh -c), the command allowlist can be bypassed through shell metacharacters. The allowlist validates only the first token of user input, but the entire raw string is handed to the shell — semicolons, pipes, backticks, and $() all work to chain arbitrary commands after a permitted one. This is a distinct issue from CVE-2025-52995 (regex partial matching, fixed in 2.33.10) and CVE-2025-52903…

Published by the source

12 Jun 2026, 22:52 UTC

Last modified by the source

21 Jul 2026, 13:54 UTC

Source last checked

26 Oct 2026, 15:27 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-8c9q-7855-wfxq

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# Patch Next advisory brief: CVE-2026-54090

Advisory: File Browser has a Command Execution Allowlist Bypass via Shell Metacharacter Injection
IDs: CVE-2026-54090, GHSA-8c9q-7855-wfxq
Record: https://patchnext.com/advisories/cve-2026-54090 (revision 1, source checked 26 Oct 2026, 15:27 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 8.7)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: github.com/filebrowser/filebrowser/v2 2.33.8. A vendor fix does not mean a deployment is fixed.

## Affected components
- Go github.com/filebrowser/filebrowser/v2: affected < 2.33.8; fixed in 2.33.8

## Suggested inspection (read-only)
- Go github.com/filebrowser/filebrowser/v2: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on github.com/filebrowser/filebrowser/v2.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-8c9q-7855-wfxq (GitHub-reviewed advisory GHSA-8c9q-7855-wfxq lists affected ranges: Go github.com/filebrowser/filebrowser/v2 >=0 <2.33.8)

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