VULNERABILITY INTELLIGENCE

CVE-2026-5163

CVSS score6.5 MEDIUM
EPSS probability0.21%
CISA KEVNot currently listed
Published2026-05-18
Last modified2026-10-14
CVSS vectorCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N

Description

Mattermost versions 11.5.x <= 11.5.1 fail to verify channel membership when processing AI-assisted message rewrites which allows an authenticated attacker to read the content of threads in private channels and direct messages they do not have access to via a crafted request to the post rewrite endpoint.. Mattermost Advisory ID: MMSA-2026-00645

Weakness classification

  • CWE-862: Missing Authorization

Primary references