CERT-FR flags security policy bypass vulnerability CVE-2026-93851 in Mattermost Server 11.7.x to 11.9.x
The CERT-FR published advisory CERTFR-2026-AVI-1409 on a vulnerability in Mattermost Server that lets an attacker bypass the security policy. It is tracked as CVE-2026-93851 and covered by vendor bulletin MMSA-2026-00742 of 28 October 2026. The article does not mention active exploitation, a CVSS score or technical details of the flaw. Administrators of affected branches should apply the vendor patches.
Entenda a falha
A vulnerabilidade
CVE-2026-93851 is a security policy bypass in Mattermost Server, per CERT-FR advisory CERTFR-2026-AVI-1409 and vendor bulletin MMSA-2026-00742 of 28 October 2026. The sources do not say which component is affected, what access an attacker needs or what they gain. Affected: 11.7.x before 11.7.11, 11.8.x before 11.8.6 and 11.9.x before 11.9.2. Fixed in 11.7.11, 11.8.6, 11.9.2 or later. No CVSS score or active exploitation is mentioned.
Como funciona
The articles give no technical detail about how the vulnerable process works, so the sequence of events and the step where it fails are not known. The only stated outcome is that an attacker can cause a bypass of the security policy.
Por que é vulnerável
The root cause is not described in the sources. They say only that the flaw allows a security policy bypass, and nothing about why it went unnoticed. The fix is delivered in the patched releases listed in the vendor bulletin, and the sources do not say what it changes.
Como foi descoberta
The articles do not say who found the flaw or how. Mattermost published bulletin MMSA-2026-00742 on 28 October 2026, and CERT-FR followed with advisory CERTFR-2026-AVI-1409 on 29 October 2026, pointing to the vendor bulletin for patches.
Explicação gerada por IA a partir da matéria e dos artigos, em 30/10/2026 14:27.
Detalhes técnicos
- Impact: security policy bypass ("contournement de la politique de sécurité").
- Affected versions: Mattermost Server 11.7.x before 11.7.11, 11.8.x before 11.8.6, and 11.9.x before 11.9.2.
Remediação
- Upgrade to Mattermost Server 11.7.11, 11.8.6, 11.9.2 or later, following the vendor security bulletin MMSA-2026-00742 (https://mattermost.com/security-updates/).
Linha do tempo
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CERT-FR flags security policy bypass vulnerability CVE-2026-93851 in Mattermost Server 11.7.x to 11.9.x
ler a análise desta fonte ocultar
The CERT-FR published advisory CERTFR-2026-AVI-1409 on a vulnerability in Mattermost Server that lets an attacker bypass the security policy. It is tracked as CVE-2026-93851 and covered by vendor bulletin MMSA-2026-00742 of 28 October 2026. The article does not mention active exploitation, a CVSS score or technical details of the flaw. Administrators of affected branches should apply the vendor patches.
Technical Details
- Impact: security policy bypass ("contournement de la politique de sécurité").
- Affected versions: Mattermost Server 11.7.x before 11.7.11, 11.8.x before 11.8.6, and 11.9.x before 11.9.2.
Remediation
- Upgrade to Mattermost Server 11.7.11, 11.8.6, 11.9.2 or later, following the vendor security bulletin MMSA-2026-00742 (https://mattermost.com/security-updates/).