CVE-2026-9708

4.9 mediumEPSS 0.4%

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

Severity

CVSS 3.1

4.9 medium

CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:H/A:N

EPSS: 0.4% chance of exploitation in the next 30 days; higher than 29% of CVEs (scores of 2026-10-31)
CWE: CWE-639
Published: 2026-07-13
Modified: 2026-07-13
Record from: the NVD, synced 2026-10-19

Affected

mattermost:mattermost_server

References

https://mattermost.com/security-updates

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