Path Traversal in github.com/gtsteffaniak/filebrowser/backend (CVE-2026-48777)
Summary
Path traversal in github.com/gtsteffaniak/filebrowser/backend (CVE-2026-48777). Risk of unauthorized operations or information disclosure. Exploitable via PATCH /public/api/resources. Mitigation: upgrade to 0.0.0-20260518193514-28e9b81e438e or later.
Original description
The description as published by the source.
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.
Source: GitHub Security Advisories (Global) NVD GitHub Advisory
Auto-generated summary
Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.
A vulnerability tracked as CVE-2026-48777 has been found in github.com/gtsteffaniak/filebrowser/backend.
Attackers can target a specific entry point like PATCH /public/api/resources over the network to misuse the product.
Risk of unauthorized operations or information disclosure.
What to do: upgrade github.com/gtsteffaniak/filebrowser/backend to 0.0.0-20260518193514-28e9b81e438e or later.
If unsure, ask your IT team or search "github.com/gtsteffaniak/filebrowser/backend CVE-2026-48777" on the vendor's site.
CVE-2026-48777 (github.com/gtsteffaniak/filebrowser/backend) — CWE-22
Attack surface: PATCH /public/api/resources / publicPatchHandler / fromPath / toPath
Patched: 0.0.0-20260518193514-28e9b81e438e — apply immediately
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.
Path traversal (CWE-22) exists in github.com/gtsteffaniak/filebrowser/backend. Attackers reach the vulnerable code path via PATCH /public/api/resources.
Check the vendor advisory for the affected versions of github.com/gtsteffaniak/filebrowser/backend. Attack surface: PATCH /public/api/resources / publicPatchHandler / fromPath / toPath.
Severity: ?. Risk of unauthorized operations or information disclosure.
Update to 0.0.0-20260518193514-28e9b81e438e.
Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.
Search webserver/proxy logs for unusual PATCH /public/api/resources requests with malformed payloads or SQL meta-characters. Run grep -r 'github.com/gtsteffaniak/filebrowser/backend' . against your dependency files (package-lock.json, requirements.txt, go.sum) to find affected services.
Response actions
Concrete steps and command examples for SOC/SRE teams to execute in order
-
1Identify exposure identify
grep -r 'github.com/gtsteffaniak/filebrowser/backend' . | grep -v node_modulesリポジトリと本番環境の依存ファイル (package-lock.json / requirements.txt / go.sum / Gemfile.lock 等) で
github.com/gtsteffaniak/filebrowser/backendを grep し、稼働しているサービス・バージョンを把握する。 -
2Hunt for indicators of compromise detect
grep 'PATCH /public/api/resources' /var/log/nginx/access.log | grep -E '(unusual_payload|sqli_pattern)'アクセスログで
PATCH /public/api/resourcesへの異常なリクエスト (不正な認証ヘッダ・SQLメタ文字)を過去 30〜90日分捜索。WAF/SIEM があれば該当パスのアラート発火履歴を確認。 -
3Apply patch patch
Upgrade github.com/gtsteffaniak/filebrowser/backend to 0.0.0-20260518193514-28e9b81e438eステージング環境で 0.0.0-20260518193514-28e9b81e438e に上げて回帰テスト → 本番反映。回帰テストはアプリの主要ハッピーパスと、Step 2 で見つけた異常検知の続報チェックを含めること。
-
4Post-deployment verification verify
Replay attack against PATCH /public/api/resources on staging to confirm patch closes the vectorパッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番では Step 2 と同じログクエリでアラート再発が無いか継続監視。
Affected packages
References
- advisory github.com
- advisory github.com
- advisory nvd.nist.gov
- package github.com
- web github.com
- web github.com
- web github.com