# Mattermost patches multiple unspecified vulnerabilities

Published: 2026-11-04 · Severity: routine · Sectors: Technology · Not tied to an actor or CVE
Canonical: https://vorant.io/reports/0fc30d5e-8156-5663-94c9-2d0cc5003c68/mattermost-patches-multiple-unspecified-vulnerabilities
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> CERT-FR advisory flags multiple vulnerabilities in Mattermost Desktop App and Server; impact unspecified by vendor, patches available.

Source: cert.cyber.gouv.fr — https://www.cert.cyber.gouv.fr/avis/CERTFR-2026-AVI-1458

## What to check

- Applies to: Not tied to a specific actor, malware or CVE, only to the sectors it covers, so it may be general reporting. Check the source before acting on it. Whether it concerns you is not assessed.

CERT-FR has published an advisory covering multiple vulnerabilities affecting Mattermost products, including the Desktop App (versions 6.3.x before 6.3.1 and 6.x before 6.2.5) and Mattermost Server (versions 11.10.x before 11.10.3, 11.11.x before 11.11.2, and 11.7.x before 11.7.12). The vendor has not specified the exact nature of the security risk, only indicating that the flaws could allow an attacker to cause an unspecified security issue.

No technical details, CVE identifiers, or exploitation status are provided in this bulletin; CERT-FR references four Mattermost Security Advisories (MMSA-2026-00800, MMSA-2026-00767, MMSA-2026-00770, MMSA-2026-00804) published between 2 and 3 November 2026 for further details. Defenders running affected Mattermost Desktop or Server versions should consult the vendor's security advisories directly and apply the corresponding updates as soon as possible, since the specific impact and exploitability cannot be assessed from this advisory alone.

There is no indication of active exploitation in the wild. Organizations using Mattermost for internal or external collaboration should prioritize patching to the fixed versions referenced in the advisory as a precaution.

Source reporting: https://www.cert.cyber.gouv.fr/avis/CERTFR-2026-AVI-1458

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