CVE-2026-19621

mediumpriority · track · 0EPSS 0.002 · 16 %ileDEUS

grimoire priorityP3 · Track

Exploitable?

—

no known exploitation

Likely / severe?

0.25% (16th) EPSS

CVSS 6.5 · medium

Is it mine?

14 products

Check your exposure

Who says so?

2 sources

cert_bund · nvd

EPSS · scored 2026-10-27

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

Technical severity, 0–10. One row per scoring source.

6.5

010

base score 0–10 · higher = more severe · hover a vector to decode

v3.16.5mediumCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:Nsecondary · responsibledisclosure@mattermost.comexploitability 2.8 · impact 3.6

v3.16mediumCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N/E:Usecondary · CVSS-BT (t0sche)

ssvc

A stakeholder decision — act, attend, or track — from exploitation and impact.

Trackcoordinatorcisa_ssvcUS

weaknesses

The CWE weakness classes this flaw belongs to.

CWE-200US

affected products (14)

Products and version ranges known to be affected.

Mattermost Mattermost< 11.10.1cert_bundDE
Mattermost Mattermost< 11.11.0cert_bundDE
Mattermost Mattermost< 11.7.10cert_bundDE
Mattermost Mattermost< 11.8.6cert_bundDE
Mattermost Mattermost< 11.9.2cert_bundDE
Mattermost Mattermost Mattermost <11.10.1< 11.10.1cert_bundDE
Mattermost Mattermost Mattermost <11.11.0< 11.11.0cert_bundDE
Mattermost Mattermost Mattermost <11.7.10< 11.7.10cert_bundDE
Mattermost Mattermost Mattermost <11.8.6< 11.8.6cert_bundDE
Mattermost Mattermost Mattermost <11.9.2< 11.9.2cert_bundDE
mattermost mattermost server= 11.10.0nvdUScpe:2.3:a:mattermost:mattermost_server:*:*:*:*:*:*:*:*
mattermost mattermost server11.7.0 → 11.7.10nvdUScpe:2.3:a:mattermost:mattermost_server:*:*:*:*:*:*:*:*
mattermost mattermost server11.8.0 → 11.8.6nvdUScpe:2.3:a:mattermost:mattermost_server:*:*:*:*:*:*:*:*
mattermost mattermost server11.9.0 → 11.9.2nvdUScpe:2.3:a:mattermost:mattermost_server:*:*:*:*:*:*:*:*

advisories (1)

Vendor and ecosystem advisories describing this.

WID-SEC-W-2026-4009Mattermost: Mehrere SchwachstellenDeutsch2026-10-15csaf · cert_bundDE
Ein Angreifer kann mehrere Schwachstellen in Mattermost ausnutzen, um Sicherheitsvorkehrungen zu umgehen, um seine Privilegien zu erhöhen, um einen Denial of Service Angriff durchzuführen, um Informationen offenzulegen, um Dateien zu manipulieren.

sources

Which sources assert this record, and when.

cert_bund nvd NVD CVE.org MITRE

published 2026-10-16modified 2026-10-27

references (1) nvd

External citations — patches, advisories, analysis.

https://mattermost.com/security-updatesVendor Advisory

scry

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