CVE-2026-30934
FileBrowser Quantum: Stored XSS in public share page via unsanitized share metadata (text/template misuse)
Impact
## Summary Stored XSS is possible via share metadata fields (e.g., `title`, `description`) that are rendered into HTML for `/public/share/<hash>` without context-aware escaping. The server uses `text/template` instead of `html/template`, allowing injected scripts to execute when victims visit the share URL. ## Details The server renders `public/index.html` using `text/template` and injects user-controlled share fields (title/description/etc.) into HTML contexts. `text/template` does not perform HTML contextual escaping like `html/template`. Because share metadata is persistent, the payload becomes stored and executes whenever a victim opens the affected share page. Relevant code paths: - `backend/http/static.go` (template rendering and share metadata assignment) - `backend/http/httpRouter.go` (template initialization) - `frontend/public/index.html` (insertion points for title/description and related fields) ## PoC 1. Login as a user with share creation permission. 2. Create a share (`POST /api/share`) with malicious metadata: - `title = </title><script>alert("xss")</script><title>` 3. Open the resulting `/public/share/<hash>` URL in a browser. 4. **Expected:** Payload is safely escaped and displayed as text. 5. **Actual:** JavaScript executes in victim's browser (stored XSS). Tested on Docker image: `gtstef/filebrowser:stable` (version `v1.2.1-stable`). ## Impact - Arbitrary script execution in application origin. - Potential account/session compromise, CSRF-like action execution, data exfiltration from authenticated contexts. - Affects anyone (including unauthenticated visitors) opening the malicious share URL. - The XSS is stored and persistent — no social engineering beyond sharing the link is required.
Affected packages
| Ecosystem | Package | Affected | Fixed in |
|---|---|---|---|
| go | github.com/gtsteffaniak/filebrowser | < 0.0.0-20260307130210-09713b32a5f6 | 0.0.0-20260307130210-09713b32a5f6 |
Affected products
| Vendor | Product | Affected versions |
|---|---|---|
| Filebrowser | Filebrowser | through 1.2.9 Versions 1.2.1, 1.3.0 |
Weakness classification
References
- NVD record
- CVE.org record
- GitHub advisory
- https://github.com/gtsteffaniak/filebrowser/releases/tag/v1.2.2-stable
- https://github.com/gtsteffaniak/filebrowser/releases/tag/v1.3.1-beta
- https://github.com/gtsteffaniak/filebrowser/security/advisories/GHSA-r633-fcgp-m532
- https://github.com/advisories/GHSA-r633-fcgp-m532
- https://nvd.nist.gov/vuln/detail/CVE-2026-30934
- https://pkg.go.dev/vuln/GO-2026-4660