PT-2026-48936 · Mattermost · Mattermost

Insomnia1102 · Published 2026-06-12 · Updated 2026-06-12 · CVE-2026-6046

NVD

CVSS v3.1

5.3

Medium

Base vector

AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:N/A:N

Mattermost versions 11.6.x <= 11.6.1, 11.5.x <= 11.5.4, 10.11.x <= 10.11.15, 10.11.x <= 10.11.16 fail to validate that a username returned during bot registration belongs to a bot account, which allows an unprivileged attacker to intercept private messages sent by plugins via direct message channels by pre-registering a user account with a predictable plugin bot username.. Mattermost Advisory ID: MMSA-2026-00649

Fix

Information Disclosure

Weakness Enumeration

CWE-200

Related Identifiers

CVE-2026-6046

Affected Products

Mattermost

References · 2

• https://mattermost.com/security-updates · Vendor Advisory
• https://nvd.nist.gov/vuln/detail/CVE-2026-6046 · Security Note