CVE-2026-3473
Low
No strong exploitation signal.
CVSS base
5.9
MEDIUM
CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:L/A:N
EPSS — probability of exploitation (30 days)
0.1%
4.5th percentile
CISA KEV
Not listed
Weakness / dates
CWE-639
Published 2026-05-22 · modified 2026-07-23
CVSS breakdown
CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:L/A:N
| Attack Vector | N | Network |
| Attack Complexity | H | High |
| Privileges Required | L | Low |
| User Interaction | N | None |
| Scope | U | Unchanged |
| Confidentiality | H | High |
| Integrity | L | Low |
| Availability | N | None |
Timeline
- 2026-05-22 — Published (NVD)
- 2026-07-23 — Last modified (NVD)
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 file ownership and access control, which allows an authenticated user to access and download files belonging to other users or teams via crafted Boards API requests using valid file IDs.. Mattermost Advisory ID: MMSA-2026-00620