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
Advisories

No advisories yet.

Fixes

Solution

Update Mattermost to versions 11.11.0, 11.10.1, 11.7.10, 11.9.2, 11.8.6 or higher.


Workaround

No workaround given by the vendor.

References
History

Fri, 16 Oct 2026 13:30:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}


Fri, 16 Oct 2026 07:30:00 +0000

Type Values Removed Values Added
Description 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
Title Mattermost leaks interactive-message integration secrets to non-admin users via post-deletion events and thread reads
Weaknesses CWE-200
References
Metrics cvssV3_1

{'score': 6.5, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N'}


Projects

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cve-icon MITRE

Status: PUBLISHED

Assigner: Mattermost

Published:

Updated: 2026-10-16T11:58:36.743Z

Reserved: 2026-08-12T14:25:35.113Z

Link: CVE-2026-19621

cve-icon Vulnrichment

Updated: 2026-10-16T11:58:30.363Z

cve-icon NVD

Status : Awaiting Analysis

Published: 2026-10-16T08:17:13.390

Modified: 2026-10-16T19:23:18.623

Link: CVE-2026-19621

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-10-16T15:30:14Z

Weaknesses