| Package | Affected versions | Patched versions |
|---|---|---|
| open-webui | < 0.9.0 | 0.9.0 |
| open webui | < 0.9.0 | 0.9.0 |
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, LdapForm model)Current main branch (commit 6fdd19bf1) and likely all versions with LDAP authentication support.
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 HTTPException(400, 'Authentication failed.')
# If bind succeeds (which it does with empty password on many servers),
# execution continues and a full session token is issued
| Metric | Value | Rationale |
|---|---|---|
| Attack Vector | Network (N) | Exploited remotely via the LDAP login endpoint |
| Attack Complexity | Low (L) | Single request with an empty password field |
| Privileges Required | None (N) | No prior authentication needed |
| User Interaction | None (N) | No victim interaction required |
| Scope | Unchanged (U) | Impact within the application's authentication boundary |
| Confidentiality | High (H) | Full access to victim's account data — chats, files, API keys, settings |
| Integrity | High (H) | Can modify victim's data, settings, send messages as victim |
| Availability | None (N) | No direct denial of service |
POST /api/v1/auths/ldap
{"user": "admin_username", "password": ""}
authenticate_user_by_email (line 507) issues a full session token for the target user.ENABLE_LDAP=True, disabled by default)Running one of these products? Scan your site to see whether it exposes a vulnerable version.
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