CVSS 3.1
4.3 mediumCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:NCVE-2026-4265
Mattermost versions 11.3.x <= 11.3.0, 11.2.x <= 11.2.2, 10.11.x <= 10.11.10 fail to validate team-specific upload_file permissions which allows a guest user to post files in channels where they lack upload_file permission via uploading files in a team where they have permission and reusing the file metadata in a POST request to a different team. Mattermost Advisory ID: MMSA-2025-00553
Severity
- EPSS
- 0.2% chance of exploitation in the next 30 days; higher than 13% 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-xpvf-6qcc-9jqc | Go | github.com/mattermost/mattermost/server/v8 | <8.0.0-20260107144005-c7f6efdfb035 | 8.0.0-20260107144005-c7f6efdfb035 |
| GHSA-xpvf-6qcc-9jqc | Go | github.com/mattermost/mattermost-server | <5.3.2-0.20260107144005-c7f6efdfb035 | 5.3.2-0.20260107144005-c7f6efdfb035 |
| GHSA-xpvf-6qcc-9jqc | Go | github.com/mattermost/mattermost-server | >=10.11.0-rc1 <10.11.11 | 10.11.11 |
| GHSA-xpvf-6qcc-9jqc | Go | github.com/mattermost/mattermost-server | >=11.2.0-rc1 <11.2.3 | 11.2.3 |
| GHSA-xpvf-6qcc-9jqc | Go | github.com/mattermost/mattermost-server | >=11.3.0-rc1 <11.3.1 | 11.3.1 |
| GO-2026-4749 | Go | github.com/mattermost/mattermost-server | >=10.11.0-rc1+incompatible <10.11.11+incompatible >=11.2.0-rc1+incompatible <11.2.3+incompatible >=11.3.0-rc1+incompatible <11.3.1+incompatible | 10.11.11+incompatible, 11.2.3+incompatible, 11.3.1+incompatible |
| GO-2026-4749 | Go | github.com/mattermost/mattermost-server/v5 | all versions | no fix published |
| GO-2026-4749 | Go | github.com/mattermost/mattermost-server/v6 | all versions | no fix published |
| GO-2026-4749 | Go | github.com/mattermost/mattermost/server/v8 | <8.0.0-20260107144005-c7f6efdfb035 | 8.0.0-20260107144005-c7f6efdfb035 |