PYSEC-2026-2720 Open WebUI Missing Access Check on Channel Members Endpoint for Standard Channels

Missing Access Check on Channel Members Endpoint for Standard Channels Affected Component Channel members listing endpoint: - backend/openwebui/routers/channels.py lines 445-507, getchannelmembersbyid Affected Versions Current main branch and likely all versions with the channels feature...

CVE-2026-56322

Capgo before 12.128.2 contains an information disclosure vulnerability in the unauthenticated /updates endpoint that resolves the defaultChannel parameter before enforcing privacy restrictions, allowing attackers to enumerate private channels and leak version/config state. Unauthenticated attacke...

CVE-2026-56323 Capgo - Unauthenticated Channel Enumeration and App Oracle via GET /channel_self

Capgo before 12.128.2 contains an information disclosure vulnerability in the /functions/v1/channelself endpoint that allows unauthenticated attackers to enumerate non-public channel names and determine app existence and subscription status. Remote attackers can send GET requests with arbitrary...

SUSE CVE-2026-21386

Mattermost versions 11.3.x = 11.3.0, 11.2.x = 11.2.2, 10.11.x = 10.11.10 fail to use consistent error responses when handling the /mute command which allows an authenticated team member to enumerate private channels they are not authorized to know about via differing error messages for nonexisten...

GO-2026-4729 Mattermost allows a removed team member to enumerate all public channels within a private team in github.com/mattermost/mattermost-server

Mattermost allows a removed team member to enumerate all public channels within a private team in github.com/mattermost/mattermost-server. NOTE: The source advisory for this report contains additional versions that could not be automatically mapped to standard Go module versions. If this is causi...

CVE-2026-21386 Private channel enumeration via /mute slash command

Mattermost versions 11.3.x = 11.3.0, 11.2.x = 11.2.2, 10.11.x = 10.11.10 fail to use consistent error responses when handling the /mute command which allows an authenticated team member to enumerate private channels they are not authorized to know about via differing error messages for nonexisten...