EUVD-2026-60542

Mattermost versions 10.11.x = 10.11.20, 11.7.x = 11.7.5 Mattermost fails to remove thread membership records when a user is removed from or leaves a team, which allows a previously removed user who is later re-invited to the team to view private channel thread root post content and metadata via t...

CVE-2026-9693 Mattermost thread memberships persist after team removal, exposing private channel thread metadata on re-invite

Mattermost versions 10.11.x = 10.11.20, 11.7.x = 11.7.5 Mattermost fails to remove thread membership records when a user is removed from or leaves a team, which allows a previously removed user who is later re-invited to the team to view private channel thread root post content and metadata via t...

CVE-2026-9693 Mattermost thread memberships persist after team removal, exposing private channel thread metadata on re-invite

Mattermost versions 10.11.x = 10.11.20, 11.7.x = 11.7.5 Mattermost fails to remove thread membership records when a user is removed from or leaves a team, which allows a previously removed user who is later re-invited to the team to view private channel thread root post content and metadata via t...

CVE-2026-16047

Mattermost versions 11.7.x ≤ 11.7.6, 10.11.x ≤ 10.11.21, and 11.8.x ≤ 11.8.3 contain an authorization flaw in the board-to-channel linking functionality. The server fails to verify that the requesting user has read access to a target channel before associating a board with it. An authenticated us...

PT-2026-76875

Name of the Vulnerable Software and Affected Versions Mattermost versions 10.11.0 through 10.11.20 Mattermost versions 11.7.0 through 11.7.5 Description The software fails to remove thread membership records when a user leaves or is removed from a team. This allows a user who is subsequently...

CVE-2026-48076

OpenReception's appointment booking software provides an end-to-end encrypted appointment booking platform. The new-client booking flow in versions 1.0.1 and prior consists of three calls: bootstrap-challenge returns a 16-bit PoW challenge with difficulty=4 leading hex zeroes, bootstrap-verify...

GHSA-73X5-H92W-XC2J Open WebUI: Private channel messages can be disclosed through cross-channel thread parent_id binding

Summary A normal authenticated user can read the content of a message in a private channel they do not belong to. GET /api/v1/channels/id/messages/messageid/thread authorizes the caller against the URL channel, but the underlying thread lookup loads the thread parent by id and returns it without...

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...

EUVD-2026-43312

Mattermost versions 11.7.x = 11.7.2, 11.6.x = 11.6.4, 10.11.x = 10.11.19 fail to verify that the channel referenced in an action cookie matches the channel of the target post, which allows an authenticated user without access to a private channel to trigger interactive post actions on posts in th...

CVE-2026-10106

Mattermost versions 11.7.x = 11.7.2, 11.6.x = 11.6.4, 10.11.x = 10.11.19 fail to verify that the channel referenced in an action cookie matches the channel of the target post, which allows an authenticated user without access to a private channel to trigger interactive post actions on posts in th...

CVE-2026-10106 Unauthorized users can trigger interactive post actions in private channels via action cookie channel mismatch in Mattermost

Mattermost versions 11.7.x = 11.7.2, 11.6.x = 11.6.4, 10.11.x = 10.11.19 fail to verify that the channel referenced in an action cookie matches the channel of the target post, which allows an authenticated user without access to a private channel to trigger interactive post actions on posts in th...

CVE-2026-10106

Mattermost vulnerable versions: 11.7.x ≤ 11.7.2, 11.6.x ≤ 11.6.4, and 10.11.x ≤ 10.11.19. The issue stems from failing to verify that the channel referenced in an action cookie matches the target post’s channel, enabling an authenticated user without access to a private channel to trigger interac...

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-2026-47176 Quest Bot: Logging module can disclose private-channel message contents to a lower-visibility log channel

Quest Bot is an opensource modern Discord Bot built for moderation, utilities and support. Prior to version 1.0.4, a user who can configure bot settings can enable logging and choose a logging channel they can read. The bot then logs deleted and edited message contents from every channel it can...

CVE-2026-5163 Missing authorization check in AI message rewrite endpoint allows access to private thread content

Mattermost versions 11.5.x = 11.5.1 fail to verify channel membership when processing AI-assisted message rewrites which allows an authenticated attacker to read the content of threads in private channels and direct messages they do not have access to via a crafted request to the post rewrite...

CVE-2026-44559

Open WebUI is a self-hosted artificial intelligence platform designed to operate entirely offline. Prior to 0.9.0, 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...

Missing Authorization

Overview open-webui is an Open WebUI Affected versions of this package are vulnerable to Missing Authorization in the getchannelmembersbyid process. An attacker can retrieve the list of users, including their IDs, names, emails, roles, and profile images, associated with a private channel by maki...

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...

Operation on a Resource after Expiration or Release

Overview mattermost-redux is a Common code API client, Redux stores, logic, utility functions for building a Mattermost client Affected versions of this package are vulnerable to Operation on a Resource after Expiration or Release in the permalink preview process. An attacker can access private...

CVE-2026-1629

A missing cache invalidation flaw has been discovered in mattermost server. Affected versions fail to invalidate cached permalink preview data when a user loses channel access which allows the user to continue viewing private channel content via previously cached permalink previews until cache...