Multiple vulnerabilities in Mattermost products (May 19, 2026)

unknownCVE-2026-6689 CVE-2026-6739 CVE-2026-7184 CVE-2026-7387 CVE-2026-3433 CVE-2026-6046

Multiple vulnerabilities have been discovered in Mattermost products. Some of them allow an attacker to cause privilege escalation, data confidentiality breach and data integrity breach.

CSIRTS triage

vendor: Mattermost product: Mattermost Privilege escalation Information disclosureOther

What: Multiple vulnerabilities in Mattermost products allow attackers to escalate privileges, breach data confidentiality, and compromise data integrity.
Who is affected: All Mattermost product deployments are affected; specific versions are not stated.
Urgency: High urgency; privilege escalation and data breach capabilities present serious risk even without active exploitation.
Action: Check Mattermost security advisory page for affected versions and apply patches or updates immediately.

AI-assisted analysis generated from the source advisory — verify against the original.

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Details

Source: CERT-FR Avis de sécurité (FR · national-cert · site)
Severity: unknown
Published: 2026-05-19
Exploitation: Not in CISA KEV at last sync
Language: Machine-translated to English — verify against the original

Original advisory: https://www.cert.ssi.gouv.fr/avis/CERTFR-2026-AVI-0610/

Exploitation outlook

EPSS (FIRST.org) estimates each CVE’s probability of exploitation in the next 30 days — here is the CSIRTS.com read on those numbers.

Low exploitation riskCVE-2026-66890.15% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 5% of all EPSS-scored CVEs.
Low exploitation riskCVE-2026-67390.26% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 18% of all EPSS-scored CVEs.
Low exploitation riskCVE-2026-71840.26% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 17% of all EPSS-scored CVEs.
Low exploitation riskCVE-2026-73870.31% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 24% of all EPSS-scored CVEs.
Low exploitation riskCVE-2026-34330.18% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 8% of all EPSS-scored CVEs.
Low exploitation riskCVE-2026-60460.19% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 9% of all EPSS-scored CVEs.
Low exploitation riskCVE-2026-69610.30% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 23% of all EPSS-scored CVEs.

Referenced CVEs

CVE	CSIRTS overview	External
CVE-2026-6689	coverage & exploitation status	NVD · CVE.org
CVE-2026-6739	coverage & exploitation status	NVD · CVE.org
CVE-2026-7184	coverage & exploitation status	NVD · CVE.org
CVE-2026-7387	coverage & exploitation status	NVD · CVE.org
CVE-2026-3433	coverage & exploitation status	NVD · CVE.org
CVE-2026-6046	coverage & exploitation status	NVD · CVE.org
CVE-2026-6961	coverage & exploitation status	NVD · CVE.org

Recent advisories for Mattermost products

A cluster of recent advisories against the same product widens the attack surface — attackers routinely chain freshly published CVEs on one product, so review these together.

unknownMultiple vulnerabilities in Mattermost products (August 14, 2026)cert-fr-avis · 2026-08-14
unknownMultiple vulnerabilities in Mattermost products (June 15, 2026)cert-fr-avis · 2026-06-15
unknownMultiple vulnerabilities in Mattermost products (May 29, 2026)cert-fr-avis · 2026-05-29
unknownMultiple vulnerabilities in Mattermost products (May 22, 2026)cert-fr-avis · 2026-05-22