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CVE-2026-87997 medium CVSS 4.3

Vulnerability in open-webui (CVE-2026-87997)

Summary

Vulnerability in open-webui (CVE-2026-87997). Risk of unauthorized operations or information disclosure. Exploitable via POST /api/chat/completions. Mitigation: upgrade to 0.11.1 or later.

Original description

The description as published by the source.

Summary

The chat-completions endpoint reads a folder id out of the request body and saves the newly created chat into that folder without checking that the caller is allowed to write there. Any authenticated user who knows a folder's id can put a chat of their own into another user's folder, including a shared folder where they hold read-only access and a folder they have no access to at all. The chat then shows up in that folder for everyone who can read it, under a title and with content the attacker controls. The dedicated chat-creation and chat-move endpoints already enforced this check, the chat-completions path did not.

Preconditions

  • An authenticated account of any role. No elevated permission, no admin involvement.
  • Folders enabled, which is the default (ENABLE_FOLDERS=true, USER_PERMISSIONS_FEATURES_FOLDERS=true).
  • The attacker needs the target folder's id. A member of a shared folder gets it from the shared-folder listing. Sharing a folder with named users is available to ordinary users by default; only wildcard public sharing is gated. A folder that was never shared has an id the attacker cannot obtain through any endpoint available to them, so those folders are not practically reachable.
  • Releases before 0.10.0 contain the same missing check but have no read path that lists a folder's chats across owners, so the injected row was never visible to anyone.

Impact

The integrity of folder contents. An attacker who cannot write to a folder can place c…

Source: NIST National Vulnerability Database 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-2026-87997 has been found in open-webui.
Attackers can target a specific entry point like POST /api/chat/completions over the network to misuse the product.
Risk of unauthorized operations or information disclosure. CVSS score: 4.3/10.
What to do: upgrade open-webui to 0.11.1 or later.
If unsure, ask your IT team or search "open-webui CVE-2026-87997" on the vendor's site.

CVE-2026-87997 (open-webui) — CWE-639 / CVSS v3 4.3
Attack vector: remote (network-reachable) / no user interaction
Attack surface: POST /api/chat/completions / POST /api/v1/chat/completions / POST /api/v1/chats/new
Patched: 0.11.1 — 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.

❓ What is the problem

A vulnerability (CWE-639) exists in open-webui. Attackers reach the vulnerable code path via POST /api/chat/completions.

📍 Affected scope

Check the vendor advisory for the affected versions of open-webui. Attack surface: POST /api/chat/completions / POST /api/v1/chat/completions / POST /api/v1/chats/new.

🔥 Severity

Severity: Medium (CVSS 4.3/10). Risk of unauthorized operations or information disclosure.

🔧 How to fix

Update to 0.11.1.

🛡️ Workaround

Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.

🔍 Detection

Search webserver/proxy logs for unusual POST /api/chat/completions 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

  1. 1
    Identify 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。

  2. 2
    Hunt for indicators of compromise detect 
    grep 'POST /api/chat/completions' /var/log/nginx/access.log | grep -E '(unusual_payload|sqli_pattern)'

    アクセスログで POST /api/chat/completions 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。

  3. 3
    Apply patch patch 
    Upgrade open-webui to 0.11.1

    ステージング環境で 0.11.1 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。

  4. 4
    Post-deployment verification verify 
    Replay attack against POST /api/chat/completions 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

pip open-webui
[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"0.11.1"}]}]

References

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