Vulnerability in open-webui (CVE-2026-87011)
Summary
Vulnerability in open-webui (CVE-2026-87011). Risk of unauthorized operations or information disclosure. Exploitable via POST /oauth/backchannel-logout. Mitigation: upgrade to 0.11.1 or later.
Original description
The description as published by the source.
Summary
The OIDC back-channel logout endpoint is unauthenticated by design, because the identity provider calls it without a browser session. Before checking whether the submitted logout token was genuine, the handler fetched the provider's discovery document and its signing keys over the network, and repeated both fetches on every request because nothing was cached. The signing-key fetch also ran as a blocking call inside the async event loop. A small number of requests carrying a worthless token was therefore enough to make the whole instance stop answering.
Preconditions
ENABLE_OAUTH_BACKCHANNEL_LOGOUT=true. The default isFalse, so a stock deployment is not affected. This setting is recommended in the Open WebUI hardening documentation, which is why the issue is treated as in scope.- At least one OIDC provider configured (
OAUTH_CLIENT_ID,OAUTH_CLIENT_SECRET,OPENID_PROVIDER_URL). - No account, credential, session or secret identifier is required. The attacker needs network access to the instance and the configured issuer string, which is published in the provider's own discovery document.
Impact
Against 0.11.0, with the identity provider answering in 150 ms, 60 concurrent requests carrying a token whose signature was four characters long stalled the async event loop for 8.3 seconds, measured against an idle baseline of 10.8 ms. For the length of that stall the process answers nothing: no chat requests, no API calls, no health check. Open WebUI…
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-2026-87011 has been found in open-webui.
Attackers can target a specific entry point like POST /oauth/backchannel-logout over the network to misuse the product.
Risk of unauthorized operations or information disclosure. CVSS score: 7.5/10.
What to do: upgrade open-webui to 0.11.1 or later.
If unsure, ask your IT team or search "open-webui CVE-2026-87011" on the vendor's site.
CVE-2026-87011 (open-webui) — CWE-405 / CVSS v3 7.5
Attack vector: remote (network-reachable) / unauthenticated / no user interaction
Attack surface: POST /oauth/backchannel-logout / False / OAUTH_CLIENT_ID / OAUTH_CLIENT_SECRET
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.
A vulnerability (CWE-405) exists in open-webui. Attackers reach the vulnerable code path via POST /oauth/backchannel-logout without authentication.
Check the vendor advisory for the affected versions of open-webui. Attack surface: POST /oauth/backchannel-logout / False / OAUTH_CLIENT_ID / OAUTH_CLIENT_SECRET.
Severity: High (CVSS 7.5/10). Risk of unauthorized operations or information disclosure.
Update to 0.11.1.
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 /oauth/backchannel-logout 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 /oauth/backchannel-logout' /var/log/nginx/access.log | grep -E '(unusual_payload|sqli_pattern)'アクセスログで
POST /oauth/backchannel-logout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 0.11.1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。
-
4Post-deployment verification verify
Replay attack against POST /oauth/backchannel-logout 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
- advisory github.com
- package github.com
- package pypi.org
- web github.com
- web github.com
- web github.com