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Path TraversalWeakness · CWE-22

CVE-2026-48777

CRITICAL · 9.3 CVSS v4.0 Published 2026-06-16
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
100/100
Remediation priority · Urgent
Remotely reachable No privileges Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
FileBrowser Quantum is a free, self-hosted, web-based file manager. Versions prior to 1.3.2-stable, 1.4.0-beta and 1.4.1-beta are vulnerable to Path Traversal through the publicPatchHandler in backend/http/public.go which joins user-controlled fromPath and toPath body fields with the trusted d.share.Path BEFORE the downstream sanitizer runs. Because filepath.Join collapses .. segments during the join, the sanitizer in resourcePatchHandler never sees the traversal and the move/copy/rename operates on a path outside the shared directory. The same root-cause pattern was patched for the bulk DELETE endpoint as CVE-2026-44542 (GHSA-fwj3-42wh-8673), but the PATCH handler with the identical pattern was not updated. A public share link with AllowModify=true is sufficient to exploit this. Anyone holding such a link can move, copy, or rename arbitrary files within the share owner's source root. This issue has been fixed in versions 1.3.3-stable and 1.4.2-beta.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

Path traversal vulnerability in FileBrowser Quantum's publicPatchHandler allows users with AllowModify=true share links to move/copy/rename files outside the shared directory. The issue is that filepath.Join collapses '..' segments before the sanitizer runs, bypassing the path validation that was intended to confine operations to the shared directory.

MitigationUpgrade to version 1.3.3-stable or 1.4.2-beta. The fix applies sanitization to user-controlled path parameters before filepath.Join, preventing '..' segment collapse from bypassing the boundary check.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
Authentication
X
User interaction
None
Scope
X

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Identify FileBrowser Quantum installation and version
    Locate the FileBrowser Quantum binary or service and run 'filebrowser --version' or check the installed package version to determine if it is below 1.3.3-stable or 1.4.2-beta
    Affected if The installed version is lower than 1.3.3-stable or 1.4.2-beta
  2. Verify sharing feature is enabled
    Examine the FileBrowser configuration file (usually filebrowser.json or config.yaml) for the 'share' or 'sharing' setting, or check the web UI settings to confirm sharing is turned on
    Affected if Sharing functionality is enabled in the configuration
  3. Confirm AllowModify setting for shared links
    Look for share link configurations or user permissions that set AllowModify=true. This may be in config files under a 'shares' or 'links' section, or visible in the admin panel under share link settings
    Affected if Any share link or user permission has AllowModify set to true
  4. Inspect publicPatchHandler configuration
    Check the FileBrowser configuration or source code references to 'publicPatchHandler' to verify this endpoint exists and is accessible for share link operations (move/copy/rename)
    Affected if The publicPatchHandler endpoint is active and accessible to share link users

If FileBrowser Quantum version is below 1.3.3-stable/1.4.2-beta, sharing is enabled with AllowModify=true on any share link, and the publicPatchHandler is accessible, the path traversal vulnerability is present.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Upgrade to version 1.3.3-stable or 1.4.2-beta. The fix applies sanitization to user-controlled path parameters before filepath.Join, preventing '..' segment collapse from bypassing the boundary check.

Recommended fix High confidence

1.3.3-stable or 1.4.2-beta

  1. Identify the current FileBrowser version to confirm it is vulnerable (< 1.3.2-stable, < 1.4.0-beta, or < 1.4.1-beta).
  2. Upgrade FileBrowser to version 1.3.3-stable (stable branch) or 1.4.2-beta (beta branch).
  3. Restart the FileBrowser service to apply the changes.
Caveat None expected for this security patch release.

Generated from the published advisory — verify against the referenced sources before acting.

Have this fixed Scoped from the published advisory
  • Consultation2.0 h
  • Implementation3.0 h
  • Testing3.0 h
  • Review / QA2.0 h
10.0 hours of engineering $1,750
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-48777 in production — separate from our analysis above.

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What this is

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What belongs here
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  • Version or environment caveats, and links to real fixes
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