CVE-2026-8823

Name: CVE-2026-8823
Creator: NVD / NIST
Published: 2026-06-22T16:16:42.853+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

LOWCVSS 3.8/10EPSS 0.23%

Last modified Jun 26, 2026

CVE-2026-8823 is a low-severity vulnerability rated 3.8/10 on the CVSS scale. Mattermost versions 11.7.x <= 11.7.0, 10.11.x <= 10.11.17 fail to validate bot targets when demoting users to guests which allows a lower-privileged administrator to degrade arbitrary bot accounts via the standard demote-user API.. Mattermost Advisory ID: MMSA-2026-00669. EPSS estimates a 0.23% chance of exploitation in the next 30 days.

Description

Mattermost versions 11.7.x <= 11.7.0, 10.11.x <= 10.11.17 fail to validate bot targets when demoting users to guests which allows a lower-privileged administrator to degrade arbitrary bot accounts via the standard demote-user API.. Mattermost Advisory ID: MMSA-2026-00669

Metrics

CVSS 3.1

3.8/10

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

EPSS Probability

0.23%

13.9th 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, < 10.11.18
Mattermost	Mattermost Server	>= 11.7.0, < 11.7.1

References

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

Timeline

Published: Jun 22, 2026
Last Modified: Jun 26, 2026
Status: Analyzed

Frequently Asked Questions

What is CVE-2026-8823?

How severe is CVE-2026-8823?

CVE-2026-8823 has a CVSS score of 3.8/10 (LOW severity). The EPSS model estimates a 0.23% probability of exploitation in the next 30 days.

How do I fix CVE-2026-8823?

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-2026-8823?

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

Scan your code now

Source: NVD / NIST