GHSA-PG7C-462J-GRXV Mattermost doesn't archive the channel before removing persistent notifications

Mattermost versions 11.6.x = 11.6.0, 11.5.x = 11.5.3, 11.4.x = 11.4.4, 10.11.x = 10.11.14 fail to archive the channel before removing persistent notifications which allows authenticated user to crash the server via timing the creation of persistent notification message between the server deleting...

GHSA-7PF2-9C95-W332 Mattermost doesn't validate file ownership and access control

Mattermost versions 11.6.x = 11.6.0, 11.5.x = 11.5.3, 11.4.x = 11.4.4, 10.11.x = 10.11.14 fail to validate file ownership and access control, which allows an authenticated user to access and download files belonging to other users or teams via crafted Boards API requests using valid file IDs...

Improper Check for Unusual or Exceptional Conditions

Overview Affected versions of this package are vulnerable to Improper Check for Unusual or Exceptional Conditions in the outgoing webhook process. An attacker can cause the server to terminate unexpectedly by sending a crafted webhook callback response containing a null attachment entry...

CVE-2026-4915

Mattermost versions 11.6.x = 11.6.0, 11.5.x = 11.5.3, 11.4.x = 11.4.4, 10.11.x = 10.11.14 fail to filter nil elements from outgoing webhook attachment payloads before processing, which allows an authenticated user to cause a denial of service server process termination via a crafted webhook...

CVE-2026-4915 Server panic via outgoing webhook responses

Mattermost versions 11.6.x = 11.6.0, 11.5.x = 11.5.3, 11.4.x = 11.4.4, 10.11.x = 10.11.14 fail to filter nil elements from outgoing webhook attachment payloads before processing, which allows an authenticated user to cause a denial of service server process termination via a crafted webhook...

EUVD-2026-31646

Mattermost versions 11.6.x = 11.6.0, 11.5.x = 11.5.3, 11.4.x = 11.4.4, 10.11.x = 10.11.14 fail to filter nil elements from outgoing webhook attachment payloads before processing, which allows an authenticated user to cause a denial of service server process termination via a crafted webhook...

CVE-2026-4915 Server panic via outgoing webhook responses

Mattermost versions 11.6.x = 11.6.0, 11.5.x = 11.5.3, 11.4.x = 11.4.4, 10.11.x = 10.11.14 fail to filter nil elements from outgoing webhook attachment payloads before processing, which allows an authenticated user to cause a denial of service server process termination via a crafted webhook...

CVE-2026-4915

Mattermost is affected in CVE-2026-4915 across multiple release streams (11.6.x <= 11.6.0, 11.5.x <= 11.5.3, 11.4.x <= 11.4.4, 10.11.x

CVE-2026-4915

Mattermost versions 11.6.x = 11.6.0, 11.5.x = 11.5.3, 11.4.x = 11.4.4, 10.11.x = 10.11.14 fail to filter nil elements from outgoing webhook attachment payloads before processing, which allows an authenticated user to cause a denial of service server process termination via a crafted webhook...

CVE-2026-4915 Server panic via outgoing webhook responses

Mattermost versions 11.6.x = 11.6.0, 11.5.x = 11.5.3, 11.4.x = 11.4.4, 10.11.x = 10.11.14 fail to filter nil elements from outgoing webhook attachment payloads before processing, which allows an authenticated user to cause a denial of service server process termination via a crafted webhook...

PT-2026-43013

Name of the Vulnerable Software and Affected Versions Mattermost version 11.6.0 Mattermost version 11.5.3 Mattermost version 11.4.4 Mattermost version 10.11.14 Description An issue exists where the system fails to filter nil elements from outgoing webhook attachment payloads before processing. Th...

Mattermost 安全漏洞

Mattermost is an open source collaboration platform from Mattermost, Inc. in the United States. A security vulnerability in Mattermost versions 11.6.0 and prior to 11.6.x, 11.5.3 and prior to 11.5.x, 11.4.4 and prior to 11.4.x, and 10.11.14 and prior to 10.11.x, which stems from a failure to filt...

CVE-2026-9354

A vulnerability was detected in NousResearch hermes-agent up to 2026.4.16. The affected element is an unknown function of the component Slack Agent/Mattermost Agent. The manipulation of the argument formatmessage results in escaping of output. The attack can be executed remotely. The exploit is n...

CVE-2026-9354 NousResearch hermes-agent Slack Agent/Mattermost Agent escape output

A vulnerability was detected in NousResearch hermes-agent up to 2026.4.16. The affected element is an unknown function of the component Slack Agent/Mattermost Agent. The manipulation of the argument formatmessage results in escaping of output. The attack can be executed remotely. The exploit is n...

CVE-2026-9354 NousResearch hermes-agent Slack Agent/Mattermost Agent escape output

A vulnerability was detected in NousResearch hermes-agent up to 2026.4.16. The affected element is an unknown function of the component Slack Agent/Mattermost Agent. The manipulation of the argument formatmessage results in escaping of output. The attack can be executed remotely. The exploit is n...

EUVD-2026-31566

A vulnerability was detected in NousResearch hermes-agent up to 2026.4.16. The affected element is an unknown function of the component Slack Agent/Mattermost Agent. The manipulation of the argument formatmessage results in escaping of output. The attack can be executed remotely. The exploit is n...

CVE-2026-9354

CVE-2026-9354 concerns NousResearch hermes-agent (up to version 2026.4.16) affecting the Slack Agent/Mattermost Agent component. The vulnerability targets an unknown function where manipulating the argument format_message results in output escaping. The issue is exploitable remotely and, per the ...

CVE-2026-9354

A vulnerability was detected in NousResearch hermes-agent up to 2026.4.16. The affected element is an unknown function of the component Slack Agent/Mattermost Agent. The manipulation of the argument formatmessage results in escaping of output. The attack can be executed remotely. The exploit is n...

PT-2026-42912

A vulnerability was detected in NousResearch hermes-agent up to 2026.4.16. The affected element is an unknown function of the component Slack Agent/Mattermost Agent. The manipulation of the argument format message results in escaping of output. The attack can be executed remotely. The exploit is...

Hermes Agent 安全漏洞

Hermes Agent is an AI agent tool developed by Nous Research, featuring a self-learning mechanism. Versions of Hermes Agent prior to 2026.4.16 contained a security vulnerability. This vulnerability stemmed from unknown functions in the Slack Agent/Mattermost Agent components, which manipulated the...