Authentication Bypass by Primary Weakness

Overview github.com/mattermost/mattermost/server/channels/app is a private-cloud Slack alternative Affected versions of this package are vulnerable to Authentication Bypass by Primary Weakness in the OAuth refresh token grant process. An attacker can maintain unauthorized access by using a valid...

EUVD-2026-43311

Mattermost versions 11.7.x = 11.7.2, 11.6.x = 11.6.4, 10.11.x = 10.11.19 fail to restrict the groupconstrained channel flag to public and private channels that support group synchronization, which allows an ordinary group or direct message member to remove all participants from the conversation v...

CVE-2026-10103

Mattermost versions 11.7.x = 11.7.2, 11.6.x = 11.6.4, 10.11.x = 10.11.19 fail to verify post ownership in the shared channel inbound sync handler, which allows an authenticated remote cluster to modify or delete posts authored by local users or other remotes via crafted sync messages referencing...

CVE-2026-10085

Mattermost versions 11.7.x = 11.7.2, 11.6.x = 11.6.4, 10.11.x = 10.11.19 fail to restrict the groupconstrained channel flag to public and private channels that support group synchronization, which allows an ordinary group or direct message member to remove all participants from the conversation v...

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 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-2026-10103 Authenticated remote cluster can modify or delete posts it does not own in Mattermost Connected Workspaces shared channels

Mattermost versions 11.7.x = 11.7.2, 11.6.x = 11.6.4, 10.11.x = 10.11.19 fail to verify post ownership in the shared channel inbound sync handler, which allows an authenticated remote cluster to modify or delete posts authored by local users or other remotes via crafted sync messages referencing...

CVE-2026-10103 Authenticated remote cluster can modify or delete posts it does not own in Mattermost Connected Workspaces shared channels

Mattermost versions 11.7.x = 11.7.2, 11.6.x = 11.6.4, 10.11.x = 10.11.19 fail to verify post ownership in the shared channel inbound sync handler, which allows an authenticated remote cluster to modify or delete posts authored by local users or other remotes via crafted sync messages referencing...

CVE-2026-10103

Mattermost versions affected: 11.7.x (up to 11.7.2), 11.6.x (up to 11.6.4), and 10.11.x (up to 10.11.19) have a flaw in the shared channel inbound sync handler that fails to verify post ownership. This allows an authenticated remote cluster to modify or delete posts authored by local users or oth...

CVE-2026-10103 Authenticated remote cluster can modify or delete posts it does not own in Mattermost Connected Workspaces shared channels

Mattermost versions 11.7.x = 11.7.2, 11.6.x = 11.6.4, 10.11.x = 10.11.19 fail to verify post ownership in the shared channel inbound sync handler, which allows an authenticated remote cluster to modify or delete posts authored by local users or other remotes via crafted sync messages referencing...

PT-2026-57653

Mattermost versions 11.7.x = 11.7.2, 11.6.x = 11.6.4, 10.11.x = 10.11.19 fail to restrict the group constrained channel flag to public and private channels that support group synchronization, which allows an ordinary group or direct message member to remove all participants from the conversation...

PT-2026-59381

Vulnerability Description In standard channels i.e., channels whose channel.type is neither group nor dm, the endpoint POST /api/v1/channels/channel id/messages/message id/update can be accessed with read permission only. When access control is set to None, the authorization check has access...,...

PT-2026-59601

rattler cache and py-rattler were vulnerable to package-cache path traversal when handling package metadata from conda channels. During cache materialization, the ratter cache code used the package record build string as part of a cache key that was joined into a filesystem path. A malicious or...

The vulnerability of the filter_allowed_access_grants() function in the Open WebUI artificial intelligence-based web interface, which allows a violator to increase their privileges

The vulnerability of the filterallowedaccessgrants function in the Open WebUI AI-based web interface is related to the lack of authorization during the processing of the final endpoint /api/v1/channels/id/members. Exploiting this vulnerability could allow a malicious actor to increase their...

PT-2026-59355

Channel Access Grants Bypass filter allowed access grants Affected Component Channel creation and update endpoints: - backend/open webui/routers/channels.py lines 291-340, create new channel - backend/open webui/routers/channels.py lines 617-638, update channel by id - backend/open...

PT-2026-59349

Summary Pin/Unpin is a write operation modifies the message's is pinned , pinned by, pinned at fields, but in standard channels it only checks read permission, allowing users with read-only access to pin/unpin any message. Details...

PT-2026-59407

Summary An IDOR vulnerability exists in the Channels feature of Open WebUI, allowing any channel member to modify messages sent by other members including administrators within the same channel. This vulnerability affects the latest version v0.8.12 of Open WebUI. Details In the update message by ...

Decidim - Private exports can be downloaded through reusable links

Description The normal downloadyourdata flow requires the requester to be logged in as the export owner, but the resulting Active Storage blob redirect URL can be replayed without authentication by anyone who obtains it. Impact Personal data exports can be retrieved through leakage channels such ...

PT-2026-59363

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...

PT-2026-59374

Deactivated Channel Members Retain Full Access to Group/DM Channels Affected Component Channel membership authorization check: - backend/open webui/models/channels.py lines 663-673, is user channel member - Used at 15 locations in backend/open webui/routers/channels.py Affected Versions Current...