CVE-2026-3115

Name: CVE-2026-3115
Creator: NVD / NIST
Published: 2026-03-26T17:16:42.66+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

MEDIUMCVSS 4.3/10EPSS 0.23%

Last modified Jun 17, 2026

CVE-2026-3115 is a medium-severity vulnerability rated 4.3/10 on the CVSS scale. Mattermost versions 11.2.x <= 11.2.2, 10.11.x <= 10.11.10, 11.4.x <= 11.4.0, 11.3.x <= 11.3.1 fail to apply view restrictions when retrieving group member IDs, which allows authenticated guest users to enumerate user IDs outside their allowed visibility scope via the group retrieval endpoint.. Mattermost Advisory ID: MMSA-2026-00594. EPSS estimates a 0.23% chance of exploitation in the next 30 days.

Description

Mattermost versions 11.2.x <= 11.2.2, 10.11.x <= 10.11.10, 11.4.x <= 11.4.0, 11.3.x <= 11.3.1 fail to apply view restrictions when retrieving group member IDs, which allows authenticated guest users to enumerate user IDs outside their allowed visibility scope via the group retrieval endpoint.. Mattermost Advisory ID: MMSA-2026-00594

Metrics

CVSS 3.1

4.3/10

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

EPSS Probability

0.23%

13.8th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-863

Affected Software

Vendor	Product	Versions
Mattermost	Mattermost Server	>= 10.11.0, < 10.11.11
Mattermost	Mattermost Server	>= 11.2.0, < 11.2.3
Mattermost	Mattermost Server	>= 11.3.0, < 11.3.2
Mattermost	Mattermost Server	11.4.0

References

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

Timeline

Published: Mar 26, 2026
Last Modified: Jun 17, 2026
Status: Analyzed

Frequently Asked Questions

What is CVE-2026-3115?

How severe is CVE-2026-3115?

CVE-2026-3115 has a CVSS score of 4.3/10 (MEDIUM severity). The EPSS model estimates a 0.23% probability of exploitation in the next 30 days.

How do I fix CVE-2026-3115?

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-2026-3115?

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

Scan your code now

Source: NVD / NIST