CVSS 6.5 (medium) · published 2026-10-16
Mattermost versions 11.10.x <= 11.10.0, 11.7.x <= 11.7.9, 11.9.x <= 11.9.1, 11.8.x <= 11.8.5 fail to strip action integration secrets from post payloads before broadcasting post-deletion web socket events and returning thread API responses, which allows an authenticated channel member to obtain server-side webhook URLs and authentication context from interactive-message posts via the post_deleted websocket event or the threads REST API.. Mattermost Advisory ID: MMSA-2026-00766
Affected products (NVD): mattermost mattermost_server
Fixed in (NVD): 11.7.10, 11.8.6, 11.9.2
Weakness: CWE-200
Source: NVD CVE-2026-19621
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