CVE-2026-9708
Incoming webhook user attribution via unvalidated webhook owner
CVSS Score
4.9
EPSS Score
0.2%
EPSS Percentile
11th
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
| CWE | CWE-639 |
| Vendor | mattermost |
| Product | mattermost |
| Published | Jul 13, 2026 |
| Last Updated | Jul 13, 2026 |
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CVSS v3 Breakdown
CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:H/A:N Attack Vector
Network
Attack Complexity
Low
Privileges Required
High
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
High
Availability
None
Affected Versions
Mattermost / Mattermost
11.7.0 ≤ 11.7.2 11.6.0 ≤ 11.6.4 10.11.0 ≤ 10.11.19
Credits
arang