CVE-2026-28735

MEDIUM EPSS 3.5%
Published May 22, 20261mo ago · Modified Jun 17, 20261w ago
5.4 CVSS 3.1
Medium
Find Similar
Published May 22, 2026 1mo ago
Last Modified Jun 17, 2026 1w ago

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

CVSS Details

Base Score
5.4
Exploitability
2.8
Impact
2.5
Vector string
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N
Attack Vector Network
Attack Complexity Low
Privileges Required Low
User Interaction None
Scope Unchanged
Confidentiality Low
Integrity Low
Availability None

Threat Intelligence

EPSS Exploit Probability
3.5% percentile
Exploit & Patch Status
No Known Exploit
No Patch Available

Weaknesses 1

CWE-863 Incorrect Authorization Authorization

Affected Products 4

VendorProductVersionRange
mattermostmattermost_server*≥10.11.0  –  <10.11.15
mattermostmattermost_server*≥11.4.0  –  <11.4.5
mattermostmattermost_server*≥11.5.0  –  <11.5.4
mattermostmattermost_server*≥11.6.0  –  <11.6.1

References 1

  • mattermost.com https://mattermost.com/security-updates
    Vendor Advisory

Remediation

No remediation data recorded yet

Check vendor advisories and the NVD entry for patch availability.