CVE-2026-48777: FileBrowser Quantum: Path Traversal in public share PATCH allows file ops outside shared directory
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.
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade
FileBrowser Quantumto a version that resolves this vulnerability.Fixed in 1.3.3-stable - Upgrade
Upgrade
FileBrowser Quantumto a version that resolves this vulnerability.Fixed in 1.4.2-beta - Compensating control
Revoke or disable any public share links with AllowModify=true (public shares that permit modifications) until the installation is upgraded to a fixed version.
Event History
Frequently Asked Questions
What is the severity of CVE-2026-48777?
CVE-2026-48777 has a severity score of 9.3, indicating a critical vulnerability.
How do I fix CVE-2026-48777?
To resolve CVE-2026-48777, upgrade to FileBrowser Quantum version 1.3.2-stable or later.
What is the nature of the vulnerability in CVE-2026-48777?
CVE-2026-48777 is a Path Traversal vulnerability that allows unauthorized file operations outside the shared directory.
Which versions of FileBrowser Quantum are affected by CVE-2026-48777?
FileBrowser Quantum versions prior to 1.3.2-stable, 1.4.0-beta, and 1.4.1-beta are affected by CVE-2026-48777.
What can attackers do with CVE-2026-48777?
Attackers exploiting CVE-2026-48777 can access or manipulate files located outside the intended shared directory.