CVE-2026-9708
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…
Does this matter?
Lower severity and a low EPSS score (0.36%). Track it; it rarely justifies an emergency change on its own.
Description
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 crafted incoming webhook configuration and payloads.. Mattermost Advisory ID: MMSA-2026-00683
- CVSS 3.1
- 4.9 MEDIUMCVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:H/A:N
- EPSS
- 0.36% probability · 29th percentile
- CISA KEV
- Not listed
- Weakness
- CWE-639
- Affected
- mattermost/mattermost server
- Source
- responsibledisclosure@mattermost.com
References
- https://mattermost.com/security-updatesVendor Advisory
Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.