CVE-2026-3473

Name: CVE-2026-3473
Creator: NVD / NIST
Published: 2026-05-22T11:16:22.477+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

HIGHCVSS 7.1/10EPSS 0.15%

Last modified Jun 17, 2026

CVE-2026-3473 is a high-severity vulnerability rated 7.1/10 on the CVSS scale. 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. EPSS estimates a 0.15% chance of exploitation in the next 30 days.

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

Metrics

CVSS 3.1

7.1/10

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:N

EPSS Probability

0.15%

4.5th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-639

Affected Software

Vendor	Product	Versions
Mattermost	Mattermost Server	>= 10.11.0, < 10.11.15
Mattermost	Mattermost Server	>= 11.4.0, < 11.4.5
Mattermost	Mattermost Server	>= 11.5.0, < 11.5.4
Mattermost	Mattermost Server	>= 11.6.0, < 11.6.1

References

https://mattermost.com/security-updatesVendor Advisory

Timeline

Published: May 22, 2026
Last Modified: Jun 17, 2026
Status: Analyzed

Frequently Asked Questions

What is CVE-2026-3473?

How severe is CVE-2026-3473?

CVE-2026-3473 has a CVSS score of 7.1/10 (HIGH severity). The EPSS model estimates a 0.15% probability of exploitation in the next 30 days.

How do I fix CVE-2026-3473?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2026-3473?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST