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CVE-2026-88005 medium CVSS 6.5

Authorization Flaw in open-webui (CVE-2026-88005)

Summary

Vulnerability in open-webui (CVE-2026-88005). Risk of unauthorized operations or information disclosure. Exploitable via OAUTH_ALLOWED_DOMAINS. Mitigation: upgrade to 0.9.0 or later.

Original description

The description as published by the source.

Summary

Open WebUI's OAuth token exchange endpoint issues a session for a provider access token without applying the email domain allowlist that the normal OAuth login callback enforces. An account whose email domain the login callback would refuse could still obtain a working session through this endpoint.

Preconditions

  • ENABLE_OAUTH_TOKEN_EXCHANGE=True. It is disabled by default, so a default deployment is not affected.
  • OAUTH_ALLOWED_DOMAINS set to something other than *. Deployments without a domain allowlist are not affected.
  • A valid, unexpired access token on the configured provider.
  • An Open WebUI account already linked to that provider subject, or an account with a matching email when OAUTH_MERGE_ACCOUNTS_BY_EMAIL is enabled. This endpoint never creates accounts, so a token for a subject with no existing account is rejected.

Impact

An admin who narrows the domain allowlist expects users outside it to lose access at their next sign-in. The login callback does deny them. Token exchange kept issuing sessions, so a user whose domain was removed retained working access as their existing account at its existing role. The endpoint cannot create an account and cannot raise anyone's role, so this grants continued access rather than new or elevated access.

Fix

fb5ef978b, released in 0.9.0, adds the same domain allowlist check to the token exchange endpoint that the login callback runs, and denies the exchange with 403 when the email domain is not all…

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-2026-88005 has been found in open-webui.
Attackers can target a specific entry point like OAUTH_ALLOWED_DOMAINS over the network to misuse the product.
Risk of unauthorized operations or information disclosure. CVSS score: 6.5/10.
What to do: upgrade open-webui to 0.9.0 or later.
If unsure, ask your IT team or search "open-webui CVE-2026-88005" on the vendor's site.

CVE-2026-88005 (open-webui) — CWE-863 / CVSS v3 6.5
Attack vector: remote (network-reachable) / unauthenticated / no user interaction
Attack surface: OAUTH_ALLOWED_DOMAINS / OAUTH_MERGE_ACCOUNTS_BY_EMAIL
Patched: 0.9.0 — 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

Incorrect authorization (CWE-863) exists in open-webui. Attackers reach the vulnerable code path via OAUTH_ALLOWED_DOMAINS without authentication.

📍 Affected scope

Check the vendor advisory for the affected versions of open-webui. Attack surface: OAUTH_ALLOWED_DOMAINS / OAUTH_MERGE_ACCOUNTS_BY_EMAIL.

🔥 Severity

Severity: Medium (CVSS 6.5/10). Risk of unauthorized operations or information disclosure.

🔧 How to fix

Update to 0.9.0.

🛡️ 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 request patterns matching this CVE's known IOCs. 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
    Apply patch patch 
    Upgrade open-webui to 0.9.0

    ステージング環境で 0.9.0 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を含めること。

  3. 3
    Post-deployment verification verify 
    Confirm patched version is live in production

    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。本番ではアクセスログ・WAF 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":"0.9.0"}]}]

References

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