Know every vulnerabilitybefore it knows you.
DevGuard continuously monitors your dependencies and alerts you when CVEs like this one affect your stack — with real-time threat intelligence built for developers.
PYSEC-2026-2720
No affected components available
Missing Access Check on Channel Members Endpoint for Standard Channels
Affected Component
Channel members listing endpoint:
backend/open_webui/routers/channels.py(lines 445-507,get_channel_members_by_id)
Affected Versions
Current main branch and likely all versions with the channels feature.
Description
The GET /api/v1/channels/{id}/members endpoint only checks membership for group and dm channel types (lines 467-469). For standard channels — including private ones — there is no channel_has_access check before returning the member list. Any authenticated user who knows a private channel's UUID can enumerate all users with access to that channel.
# Line 467-469: only group/dm channels are checked
if channel.type in ['group', 'dm']:
if not Channels.is_user_channel_member(channel.id, user.id, db=db):
raise HTTPException(...)
# Standard channels fall through with NO access check
Compare with other channel endpoints (e.g., get_channel_messages at line 688) which correctly call channel_has_access(user.id, channel, permission='read') for standard channels.
CVSS 3.1 Breakdown
| Metric | Value | Rationale | |--------|-------|-----------| | Attack Vector | Network (N) | Exploited remotely via API call | | Attack Complexity | Low (L) | Single API call, no special conditions | | Privileges Required | Low (L) | Requires a valid user account | | User Interaction | None (N) | No victim interaction required | | Scope | Unchanged (U) | Impact is within the channel authorization boundary | | Confidentiality | Low (L) | Leaks user identities and details for a private channel | | Integrity | None (N) | No data modification | | Availability | None (N) | No denial of service |
Attack Scenario
- Attacker obtains a private standard channel's UUID (via logs, browser history, URL observation, or other API responses).
- Attacker calls
GET /api/v1/channels/{id}/members. - The server returns the full list of permitted users including their IDs, names, emails, roles, and profile images.
- The attacker has no access to the channel's messages (those endpoints check access correctly), but now knows exactly who does.
Impact
- Leaks the identity and personal details of every user with access to a private channel
- Reveals organizational structure and project assignments
- Enables targeted social engineering against channel members
Preconditions
- Channels feature must be enabled (disabled by default)
- Attacker must know the channel UUID (not guessable, but obtainable through indirect means)
The vulnerability can be exploited over the network without needing physical access. It is easy for an attacker to exploit this vulnerability. An attacker needs basic access or low-level privileges. No user interaction is needed for the attacker to exploit this vulnerability. The impact is confined to the system where the vulnerability exists. There is a low impact on the confidentiality of the information.
Exploitation attempts have been detected. Elevated vigilance and prompt remediation are advised.
The exploit probability is very low. The vulnerability is unlikely to be exploited in the next 30 days.
We did not find any exploit available. Neither in GitHub repositories nor in the Exploit-Database.
Browse More
Continuously monitor your dependencies and get alerted when vulnerabilities like this one affect your stack.
Checkout DevGuard