File Browser has an access rule bypass via HasPrefix without trailing separator in path matching

Exploitation

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

CVSS 4.0

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

EPSS

• CVE-2026-35605: 0.39% estimated exploitation activity in the next 30 days; percentile 33.36 (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.

Hi, The Matches() function in rules/rules.go uses strings.HasPrefix() without a trailing directory separator when matching paths against access rules. A rule for /uploads also matches /uploadsbackup/, granting or denying access to unintended directories. Verified against v2.62.2 (commit 860c19d). Details At rules/rules.go:29-35: func (r Rule) Matches(path string) bool { if r.Regex { return r.Regexp.MatchString(path) } return strings.HasPrefix(path, r.Path) } When a rule has Path: "/uploads", any path starting with /uploads matches, including /uploadsbackup/secret.txt. The regex variant at line 31 uses proper matching, but the non-regex path uses a prefix check without ensuring the match ends at a directory boundary. The Check() function at http/data.go:29-48 iterates all rules with last-match-wins semantics. No secondary validation exists beyond this prefix check. PoC Admin configures: allow rule Path: "/shared" for a restricted user. Filesystem contains: - /shared/ (intended to be…

Published by the source

8 Apr 2026, 00:04 UTC

Last modified by the source

8 Apr 2026, 00:04 UTC

Source last checked

26 Oct 2026, 15:19 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-5q48-q4fm-g3m6

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# Patch Next advisory brief: CVE-2026-35605

Advisory: File Browser has an access rule bypass via HasPrefix without trailing separator in path matching
IDs: CVE-2026-35605, GHSA-5q48-q4fm-g3m6
Record: https://patchnext.com/advisories/cve-2026-35605 (revision 1, source checked 26 Oct 2026, 15:19 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 6.3)
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 2.63.1. A vendor fix does not mean a deployment is fixed.

## Affected components
- Go github.com/filebrowser/filebrowser/v2: affected < 2.63.1; fixed in 2.63.1

## 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-5q48-q4fm-g3m6 (GitHub-reviewed advisory GHSA-5q48-q4fm-g3m6 lists affected ranges: Go github.com/filebrowser/filebrowser/v2 >=0 <2.63.1)

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