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© 2026 FAUCET Technologies LLC. All rights reserved.

CVE-2026-3473

29
FAUCET Score

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

First published: May 22, 2026Last modified: May 22, 2026

Impacted Technologies

VendorProductVersion(s)CPE
>= 10.11.0, < 10.11.15CPE matchmatch criteria
cpe:2.3:a:mattermost:mattermost_server:*:*:*:*:*:*:*:*
>= 11.4.0, < 11.4.5CPE matchmatch criteria
cpe:2.3:a:mattermost:mattermost_server:*:*:*:*:*:*:*:*
>= 11.5.0, < 11.5.4CPE matchmatch criteria
cpe:2.3:a:mattermost:mattermost_server:*:*:*:*:*:*:*:*
>= 11.6.0, < 11.6.1CPE matchmatch criteria
cpe:2.3:a:mattermost:mattermost_server:*:*:*:*:*:*:*:*
>= 10.11.0, <= 10.11.14CPE match
cpe:2.3:a:mattermost:mattermost:*:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

5.9MEDIUM

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

Attack Vector
NETWORK
Attack Complexity
HIGH
Privileges Required
LOW
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
HIGH
Integrity Impact
LOW
Availability Impact
NONE
Exploitability Score
1.6
Impact Score
4.2
CvssVersion
3.1

Exploit Intelligence

EPSS Score
0.15%
Probability of exploitation in next 30 days
EPSS Percentile
4.6%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0015 is in the 0th percentile among its peer group of 17,844 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.3 Bluesky, 0.1 Mastodon, and 0.2 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.1 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (4)

gopatch availablevia ghsa
Product: github.com/mattermost/mattermost-serverFixed in: 11.6.1
gopatch availablevia ghsa
Product: github.com/mattermost/mattermost-serverFixed in: 11.5.4
gopatch availablevia ghsa
Product: github.com/mattermost/mattermost-serverFixed in: 11.4.5
gopatch availablevia ghsa
Product: github.com/mattermost/mattermost-serverFixed in: 10.11.15

Vendor Advisories (1)

goGHSA-7pf2-9c95-w332high

Mattermost doesn't validate file ownership and access control

May 26, 2026

References

mattermost.com / security-updates
Vendor Advisory