CVSS 3.1
5.4 mediumCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:NCVE-2026-28735
Medium (5.4) in mattermost mattermost server. EPSS 0.1% chance of exploitation in the next 30 days. Fixed in github.com/mattermost/mattermost-server 10.11.15, 10.11.15+incompatible, 11.4.5.
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
Severity
- EPSS
- 0.1% chance of exploitation in the next 30 days; higher than 3% of CVEs (scores of 2026-10-31)
- CWE
- CWE-863
- Published
- Modified
- Record from
- the NVD, synced
Affected
- mattermost:mattermost_server
Packages (OSV)
| Advisory | Ecosystem | Package | Affected | Fixed in |
|---|---|---|---|---|
| GHSA-r5vf-grcx-5vqp | Go | github.com/mattermost/mattermost-server | >=11.6.0 <11.6.1 | 11.6.1 |
| GHSA-r5vf-grcx-5vqp | Go | github.com/mattermost/mattermost-server | >=11.5.0 <11.5.4 | 11.5.4 |
| GHSA-r5vf-grcx-5vqp | Go | github.com/mattermost/mattermost-server | >=11.4.0 <11.4.5 | 11.4.5 |
| GHSA-r5vf-grcx-5vqp | Go | github.com/mattermost/mattermost-server | >=10.11.0 <10.11.15 | 10.11.15 |
| GHSA-r5vf-grcx-5vqp | Go | github.com/mattermost/mattermost-plugin-github | <1.0.1-0.20260318132218-6e6b740c4852 | 1.0.1-0.20260318132218-6e6b740c4852 |
| GO-2026-5839 | Go | github.com/mattermost/mattermost-plugin-github | <1.0.1-0.20260318132218-6e6b740c4852 | 1.0.1-0.20260318132218-6e6b740c4852 |
| GO-2026-5839 | Go | github.com/mattermost/mattermost-server | >=10.11.0+incompatible <10.11.15+incompatible >=11.4.0+incompatible <11.4.5+incompatible >=11.5.0+incompatible <11.5.4+incompatible >=11.6.0+incompatible <11.6.1+incompatible | 10.11.15+incompatible, 11.4.5+incompatible, 11.5.4+incompatible, 11.6.1+incompatible |