Authentication Bypass in open-webui (CVE-2026-44551)
Summary
Authentication bypass in open-webui (CVE-2026-44551). Confidential information can be exposed externally. Exploitable via POST /api/v1/auths/ldap. Mitigation: upgrade to 0.9.0 or later.
Original description
The description as published by the source.
LDAP Empty Password Authentication Bypass
Affected Component
LDAP authentication endpoint:
backend/open_webui/routers/auths.py(lines 468-477, user bind with empty password)backend/open_webui/models/auths.py(lines 58-60,LdapFormmodel)
Affected Versions
Current main branch (commit 6fdd19bf1) and likely all versions with LDAP authentication support.
Description
The LDAP authentication endpoint does not validate that the submitted password is non-empty before performing a Simple Bind against the LDAP server. Per RFC 4513 Section 5.1.2, a Simple Bind with a valid DN and an empty password constitutes an "unauthenticated simple authentication" — many LDAP servers (including OpenLDAP in default configuration and some Active Directory setups) return success (resultCode 0) for this operation.
The LdapForm Pydantic model accepts password: str with no minimum length constraint, so an empty string passes validation. The subsequent Connection.bind() call succeeds on vulnerable LDAP servers, and the application issues a full session token for the target user.
# models/auths.py:58-60 — no min_length on password
class LdapForm(BaseModel):
user: str
password: str
# auths.py:469-477 — empty password reaches LDAP bind
connection_user = Connection(
server,
user_dn,
form_data.password, # can be ""
auto_bind='NONE',
authentication='SIMPLE',
)
if not await asyncio.to_thread(connection_user.bind):
raise HTTPExcept…
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-2026-44551 has been found in open-webui.
Attackers can target a specific entry point like POST /api/v1/auths/ldap over the network to misuse the product.
Confidential information can be exposed externally. CVSS score: 9.1/10.
What to do: upgrade open-webui to 0.9.0 or later.
If unsure, ask your IT team or search "open-webui CVE-2026-44551" on the vendor's site.
CVE-2026-44551 (open-webui) — CWE-287 / CVSS v3 9.1
Attack vector: remote (network-reachable) / unauthenticated / no user interaction
Attack surface: POST /api/v1/auths/ldap / LdapForm / authenticate_user_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.
Authentication bypass (CWE-287) exists in open-webui. Attackers reach the vulnerable code path via POST /api/v1/auths/ldap without authentication.
Check the vendor advisory for the affected versions of open-webui. Attack surface: POST /api/v1/auths/ldap / LdapForm / authenticate_user_by_email.
Severity: Critical (CVSS 9.1/10). Confidential information can be exposed externally.
Update to 0.9.0.
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/auths/ldap 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/auths/ldap' /var/log/nginx/access.log | grep -E '(unusual_payload|sqli_pattern)'アクセスログで
POST /api/v1/auths/ldap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 0.9.0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/auths/ldap 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