CVE-2026-20796

LOW

3.1

Description

Mattermost versions 10.11.x <= 10.11.9 fail to properly validate channel membership at the time of data retrieval which allows a deactivated user to learn team names they should not have access to via a race condition in the /common_teams API endpoint.. Mattermost Advisory ID: MMSA-2025-00549

CVE Details

CVSS v3.1 Score3.1

SeverityLOW

CVSS VectorCVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:N/A:N

Attack VectorNETWORK

ComplexityHIGH

Privileges RequiredLOW

User InteractionNONE

Published2/13/2026

Last Modified2/23/2026

Sourcenvd

Honeypot Sightings0

Affected Products

mattermost:mattermost_server

Weaknesses (CWE)

CWE-367

References

https://mattermost.com/security-updates(responsibledisclosure@mattermost.com)

IOC Correlations

No correlations recorded

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