File Browser has incorrect access control for public directory shares via rule path rebasing

Exploitation

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

CVSS

7.5 · CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

EPSS

• CVE-2026-54091: 0.52% estimated exploitation activity in the next 30 days; percentile 43.96 (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.

Summary File Browser's public share handlers rebase the share owner's filesystem root to the shared directory and then evaluate descendant paths against the owner's global and per-user rules using the rebased relative path instead of the original path relative to the owner's scope. As a result, an attacker who knows a public directory share URL can access files and subdirectories that the owner explicitly blocked with rules, as long as those blocked paths are located underneath the shared directory. In the simplest case this is an unauthenticated information disclosure through GET /api/public/share/ and GET /api/public/dl/. Details The public share flow first resolves the original shared path under the owner's filesystem, but then switches d.user.Fs to a new BasePathFs rooted at the shared directory. The follow-up authorization check is still performed by d.Check, which compares the request path to rule strings using prefix matching. When the share target is a directory, the path…

Published by the source

12 Jun 2026, 21:53 UTC

Last modified by the source

21 Jul 2026, 14:43 UTC

Source last checked

26 Oct 2026, 15:27 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-j9jx-hp4c-ghhh

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# Patch Next advisory brief: CVE-2026-54091

Advisory: File Browser has incorrect access control for public directory shares via rule path rebasing
IDs: CVE-2026-54091, GHSA-j9jx-hp4c-ghhh
Record: https://patchnext.com/advisories/cve-2026-54091 (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 7.5)
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 2.63.6. A vendor fix does not mean a deployment is fixed.

## Affected components
- Go github.com/filebrowser/filebrowser/v2: affected <= 2.63.5; fixed in 2.63.6

## 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-j9jx-hp4c-ghhh (GitHub-reviewed advisory GHSA-j9jx-hp4c-ghhh lists affected ranges: Go github.com/filebrowser/filebrowser/v2 >=0 <=2.63.5)

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