Vulnerability in open-webui (CVE-2026-45402)
Summary
Vulnerability in open-webui (CVE-2026-45402). Confidential information can be exposed externally. Exploitable via POST /api/v1/folders/{id}/update. Mitigation: upgrade to 0.9.5 or later.
Original description
The description as published by the source.
Cross-User File Access via Unchecked file_id in Folder Knowledge and Knowledge-Base Attach Endpoints
Summary
Multiple endpoints accept a user-supplied file_id and attach the referenced file to a resource the caller controls (folder knowledge, knowledge-base contents) without verifying that the caller owns or has been granted access to the file. The file's content then becomes reachable through the downstream RAG / file-content paths, allowing any authenticated user to exfiltrate any other user's private file — and on the knowledge-base path, also to overwrite it — given knowledge of the file's UUID.
Affected code paths
Path 1 — Folder knowledge ingestion via folders.update
backend/open_webui/routers/folders.py:156 — POST /api/v1/folders/{id}/update accepts a FolderUpdateForm whose data: Optional[dict] field is written verbatim into the folder. The folder consumer at backend/open_webui/utils/middleware.py:2409 spreads folder.data['files'] directly into form_data['files'] for the next chat completion, which becomes RAG context. There is no per-file ownership check at the writer (the update handler) and no per-file ownership check at the reader (the middleware folder consumer) — only the folder list endpoint (folders.py:78-94) cleans up by stripping inaccessible files, and that runs lazily at folder-list time rather than at chat time. An attacker with a victim's file UUID can write data: {"files": [{"id": "", "type": "file"}]} into their…
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-2026-45402 has been found in open-webui.
Attackers can target a specific entry point like POST /api/v1/folders/{id}/update over the network to misuse the product.
Confidential information can be exposed externally. CVSS score: 8.1/10.
What to do: upgrade open-webui to 0.9.5 or later.
If unsure, ask your IT team or search "open-webui CVE-2026-45402" on the vendor's site.
CVE-2026-45402 (open-webui) — CWE-639 / CVSS v3 8.1
Attack vector: remote (network-reachable) / no user interaction
Attack surface: POST /api/v1/folders/{id}/update / file_id / folders.update / FolderUpdateForm
Patched: 0.9.5 — 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.
A vulnerability (CWE-639) exists in open-webui. Attackers reach the vulnerable code path via POST /api/v1/folders/{id}/update.
Check the vendor advisory for the affected versions of open-webui. Attack surface: POST /api/v1/folders/{id}/update / file_id / folders.update / FolderUpdateForm.
Severity: High (CVSS 8.1/10). Confidential information can be exposed externally.
Update to 0.9.5.
Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.
Search webserver/proxy logs for unusual POST /api/v1/folders/{id}/update requests with malformed payloads or SQL meta-characters. Run grep -r 'open-webui' . 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 'open-webui' . | 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
open-webui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 'POST /api/v1/folders/{id}/update' /var/log/nginx/access.log | grep -E '(unusual_payload|sqli_pattern)'アクセスログで
POST /api/v1/folders/{id}/update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 open-webui to 0.9.5ステージング環境で 0.9.5 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 POST /api/v1/folders/{id}/update 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 nvd.nist.gov
- package github.com
- web github.com
- web github.com
- web github.com