CVE-2026-28735

Published May 22, 2026

Last updated 9 days ago

Overview

Description
Mattermost versions 11.6.x <= 11.6.0, 11.5.x <= 11.5.3, 11.4.x <= 11.4.4, 10.11.x <= 10.11.14 fail to validate the OAuth token scope on the callback which allows an authenticated Mattermost user to gain access to private repositories via modifying the scope parameter in the GitHub authorization URL.. Mattermost Advisory ID: MMSA-2026-00628
Source
responsibledisclosure@mattermost.com
NVD status
Analyzed
Products
mattermost_server

Risk scores

CVSS 3.1

Type
Secondary
Base score
5.4
Impact score
2.5
Exploitability score
2.8
Vector string
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N
Severity
MEDIUM

Weaknesses

responsibledisclosure@mattermost.com
CWE-863

Social media

Hype score
Not currently trending

Configurations

References

Sources include official advisories and independent security research.