Mattermost MS Teams plugin: Mehrere Schwachstellen ermöglichen Denial of Service
WID-SEC-2026-0692 · first 11.03.2026 · updated 10.04.2026 · CVSS 4,3
What it is about
Mattermost ist ein webbasierter Instant-Messaging-Dienst. Ein Angreifer kann mehrere Schwachstellen im Mattermost MS Teams plugin ausnutzen, um einen Denial of Service Angriff durchzuführen.
Under what conditions?
The BSI does not name any particular preconditions. Exploitable remotely according to the BSI.
What can happen in the worst case
An attacker could use the vulnerability to
- einen Denial of Service Angriff durchzuführen
Am I affected?
Affected according to the BSI:
- Mattermost Mattermost MS Teams plugin <2.3.2.0
The installed version is usually shown under “Help → About” or in the device’s admin interface.
What helps?
Update to at least:
- Mattermost Mattermost MS Teams plugin 2.3.2.0
Is the vulnerability already being exploited?
None of the CVEs is in the CISA catalogue of exploited vulnerabilities. That does not mean there are no attacks, only that none are documented.
Information and sources
CVE: CVE-2026-21388, CVE-2026-24661
Source: BSI warning and information service (CERT-Bund); CISA. The assessment of the conditions is my reading of the BSI text; the external pages are in their original language.