CVE-2026-28735 — GitHub OAuth Scope Validation
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 authenticate…
Published: 2026-05-22 · CVSS: 5.4 · CVSS 3.1
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: CVE Program · Revision 8b16575c39f1e1810c5e863010da073d2d3285e7