CVE-2026-10542 Playbooks channel action update validation issue

Mattermost versions 11.9.x = 11.9.0, 11.8.x = 11.8.4, 11.7.x = 11.7.7, 10.11.x = 10.11.22 fail to validate channel action ownership which allows channel managers to update actions in other channels via the channel action update endpoint.. Mattermost Advisory ID: MMSA-2026-00692...

CVE-2026-16049

Mattermost Plugins versions =11.8 10.20.11 11.5.7.0 The Mattermost GitLab plugin fails to verify channel permissions when processing API requests with a caller-supplied postid, and fails to validate the weburl parameter against the configured GitLab instance, which allows an authenticated attacke...

EUVD-2026-60209

Mattermost Plugins versions =11.8 10.20.11 11.5.7.0 The Mattermost GitLab plugin fails to verify channel permissions when processing API requests with a caller-supplied postid, and fails to validate the weburl parameter against the configured GitLab instance, which allows an authenticated attacke...

CVE-2026-16049 _GitLab Plugin allows cross-channel post injection and phishing via missing channel permission checks in issue API endpoints_

Mattermost Plugins versions =11.8 10.20.11 11.5.7.0 The Mattermost GitLab plugin fails to verify channel permissions when processing API requests with a caller-supplied postid, and fails to validate the weburl parameter against the configured GitLab instance, which allows an authenticated attacke...

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...

Authorization Bypass Through User-Controlled Key

Overview open-webui is an Open WebUI Affected versions of this package are vulnerable to Authorization Bypass Through User-Controlled Key via the getmessagesbyparentid process. An attacker can access the content, channel ID, and author metadata of messages in private channels they do not belong t...

PYSEC-2026-2711 Open WebUI's Channel Access Grants Bypass filter_allowed_access_grants

Channel Access Grants Bypass filterallowedaccessgrants Affected Component Channel creation and update endpoints: - backend/openwebui/routers/channels.py lines 291-340, createnewchannel - backend/openwebui/routers/channels.py lines 617-638, updatechannelbyid - backend/openwebui/models/channels.py...

PYSEC-2026-2732 Open WebUI: Deactivated Channel Members Retain Full Access to Group/DM Channels

Deactivated Channel Members Retain Full Access to Group/DM Channels Affected Component Channel membership authorization check: - backend/openwebui/models/channels.py lines 663-673, isuserchannelmember - Used at 15 locations in backend/openwebui/routers/channels.py Affected Versions Current main...

EUVD-2026-43308

Mattermost versions 11.7.x = 11.7.2, 11.6.x = 11.6.4, 10.11.x = 10.11.19 fail to validate that an assigned incoming webhook user has access to the target team or channel, which allows a requester with webhook management permissions to create posts or direct messages attributed to another user via...

PT-2026-57655

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-2026-44561

Open WebUI is a self-hosted artificial intelligence platform designed to operate entirely offline. Prior to 0.9.0, the isuserchannelmember function checks whether a ChannelMember row exists but does not check the isactive field. When a user is deactivated from a group or DM channel removed by the...

CVE-2026-44569

Open WebUI is a self-hosted artificial intelligence platform designed to operate entirely offline. Prior to 0.6.19, there's an IDOR in the channels message management system that allows authenticated users to modify or delete any message within channels they have read access to. The vulnerability...

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-2026-44569 Open WebUI: Insecure Message Access Breaks Authorization

Open WebUI is a self-hosted artificial intelligence platform designed to operate entirely offline. Prior to 0.6.19, there's an IDOR in the channels message management system that allows authenticated users to modify or delete any message within channels they have read access to. The vulnerability...

CVE-2026-44558 Open WebUI: Channel Access Grants Bypass filter_allowed_access_grants

Open WebUI is a self-hosted artificial intelligence platform designed to operate entirely offline. Prior to 0.9.0, the channel router does not call filterallowedaccessgrants on either create or update paths. A non-admin user who can create group channels or who owns a channel can submit arbitrary...

CVE-2026-44558 Open WebUI: Channel Access Grants Bypass filter_allowed_access_grants

Open WebUI is a self-hosted artificial intelligence platform designed to operate entirely offline. Prior to 0.9.0, the channel router does not call filterallowedaccessgrants on either create or update paths. A non-admin user who can create group channels or who owns a channel can submit arbitrary...

CVE-2026-44558

Open WebUI contains a vulnerability in the channel access grants path prior to version 0.9.0. The channel router does not call filter_allowed_access_grants on create or update, allowing a non-admin user who can create or own a group channel to submit arbitrary access grants (including public wild...

CVE-2026-44558 Open WebUI: Channel Access Grants Bypass filter_allowed_access_grants

Open WebUI is a self-hosted artificial intelligence platform designed to operate entirely offline. Prior to 0.9.0, the channel router does not call filterallowedaccessgrants on either create or update paths. A non-admin user who can create group channels or who owns a channel can submit arbitrary...

CVE-2026-44561 Open WebUI: Deactivated Channel Members Retain Full Access to Group/DM Channels

Open WebUI is a self-hosted artificial intelligence platform designed to operate entirely offline. Prior to 0.9.0, the isuserchannelmember function checks whether a ChannelMember row exists but does not check the isactive field. When a user is deactivated from a group or DM channel removed by the...

Open WebUI 安全漏洞

Open WebUI is an extensible, feature-rich, and user-friendly self-hosted WebUI under open source. Versions of Open WebUI prior to 0.9.0 contained security vulnerabilities. These vulnerabilities stemmed from the GET /api/v1/channels/id/members endpoint, which only checked group and DM channel type...