PT-2026-115512 · Mattermost · Mattermost

CVE-2026-18799

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Published

2026-10-16

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Updated

2026-10-16

CVSS v3.1

4.3

Medium

VectorAV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N
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 restrict Slack import account binding to system administrator-initiated imports which allows an authenticated attacker with team admin privileges to force-add existing Mattermost users to their team and forge posts attributed to those users' identities via a crafted Slack export containing target users' email addresses.. Mattermost Advisory ID: MMSA-2026-00757

Fix

Missing Authorization

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Weakness Enumeration

Related Identifiers

CVE-2026-18799

Affected Products

Mattermost