CVE-2026-19621

medium

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…

Vendor / product: Mattermost — mattermost server

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

CVSS

6.5

6.5 (CVSS v3.1)

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

Severity source: NVD CVSS v3.1 (responsibledisclosure@mattermost.com)

Timeline (UTC)

Published: 2026-10-16 08:17

Modified: 2026-10-27 20:59

NVD status: Analyzed

Last synced 18 hours ago

Verified against the source API 2026-10-28 11:30 UTC

Exploitation

Not listed in CISA KEV (as of last catalog sync)

Absence from KEV does not mean a CVE is not exploited. Exploitation status: unknown (no authoritative evidence in our sources).

Affected products

mattermost / mattermost_server ≥11.7.0 <11.7.10, ≥11.8.0 <11.8.6, ≥11.9.0 <11.9.2, 11.10.0

Weakness classification (CWE)

CWE-200

Source: NVD / CISA. “NVD-CWE-Other” and “NVD-CWE-noinfo” mean NVD could not assign a specific weakness.

Mitigation & advisories

Vendor advisory: https://mattermost.com/security-updates

References

https://mattermost.com/security-updates responsibledisclosure@mattermost.com

Data sources

NVD CVE API 2.0 — fetched 2026-10-28 11:30 UTC · record ↗

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CVE-2026-19621

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