FileBrowser: Symlink following escapes user scope allowing arbitrary file read outside the served directory

Exploitation

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

CVSS

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

EPSS

• CVE-2026-116682: 0.54% estimated exploitation activity in the next 30 days; percentile 45.26 (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 read paths resolve symbolic links with `filepath.EvalSymlinks` and then operate on the resolved target without re-checking that the target still lies inside the user's source/scope. A symlink located inside a user's accessible directory that points outside the scope (for example to `/etc/passwd`, another tenant's directory, SSH keys, or container secrets) is followed transparently, and its contents are served through the normal download, preview, media, and OnlyOffice endpoints. Any authenticated user with download access can read files anywhere the server process can, whenever such a symlink is reachable in their scope. The same symlink-following read path is used by the public share endpoints, which are authorized only by a share hash and not by any account, so when a public share exposes a directory that contains such a symlink, an unauthenticated attacker holding only the share link reads files outside the scope with no credential.

Details **1. Symlink…

Published by the source

27 Oct 2026, 21:04 UTC

Last modified by the source

27 Oct 2026, 21:15 UTC

Source last checked

28 Oct 2026, 06:30 UTC

1. Revision 2 · amended · 28 Oct 2026

   Amended from osv record GHSA-mgqf-5mf5-prfj

2. Revision 1 · created · 27 Oct 2026

   Published from ghsa record GHSA-mgqf-5mf5-prfj

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# Patch Next advisory brief: CVE-2026-116682

Advisory: FileBrowser: Symlink following escapes user scope allowing arbitrary file read outside the served directory
IDs: CVE-2026-116682, GHSA-mgqf-5mf5-prfj
Record: https://patchnext.com/advisories/cve-2026-116682 (revision 2, source checked 28 Oct 2026, 06:30 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 8.6)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: github.com/gtsteffaniak/filebrowser/backend 0.0.0-20260814233832-4126edeb07a0. A vendor fix does not mean a deployment is fixed.

## Affected components
- Go github.com/gtsteffaniak/filebrowser/backend: affected < 0.0.0-20260814233832-4126edeb07a0; fixed in 0.0.0-20260814233832-4126edeb07a0

## Suggested inspection (read-only)
- Go github.com/gtsteffaniak/filebrowser/backend: 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/gtsteffaniak/filebrowser/backend.
- 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-mgqf-5mf5-prfj (GitHub-reviewed advisory GHSA-mgqf-5mf5-prfj lists affected ranges: Go github.com/gtsteffaniak/filebrowser/backend >=0 <0.0.0-20260814233832-4126edeb07a0)
- Verified: https://osv.dev/vulnerability/GHSA-mgqf-5mf5-prfj (OSV record GHSA-mgqf-5mf5-prfj lists affected ranges: Go github.com/gtsteffaniak/filebrowser/backend >=0 <0.0.0-20260814233832-4126edeb07a0 (fixed))

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