CVE-2026-8823

ℹ️ low

Summary

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

CVSS Score

3.8

Low

EPSS Score

0.2

Exploit Probability

Published Date

2026-06-22

First Seen: 2026-06-25

📊 Relative Risk Intelligence

This CVE is Lower Risk - more severe than 4.4% of all 330,193 vulnerabilities in our database.

#315,624

Below average severity

Severity Percentile

🎯 CISA SSVC Assessment Updated: Jun 22, 2026

🔍 Exploitation Status

None

No known exploits

⚙️ Automatable

Requires human interaction

💥 Technical Impact

Partial

Limited system impact

🏆 Discovered By

Edgar Bellot Micó

SSVC data provided by CISA

Last Modified 2026-06-26

Source NVD 🔗

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

CWE IDs (Weakness Types)

CWE-863

📦 Affected Products 2

Vendor	Product	Status	Affected Versions
mattermost	mattermost_server	Affected	> 10.11.0 < 10.11.18
mattermost	mattermost_server	Affected	> 11.7.0 < 11.7.1

🔗 References 1

https://mattermost.com/security-updates

Vendor Advisory

🔗 Related CVEs 6

CVE ID	Severity	CVSS	EPSS	Summary	Published
CVE-2026-5139	🔶 medium	5.4	0.2	Mattermost versions 11.7.x <= 11.7.0, 11.6.x <= 11.6.2, 11.5.x <= 11.5.5, 10.11.x <= 10.11.17 fail to enforce administra...	2026-06-22
CVE-2026-6062	🔶 medium	6.4	0.2	Mattermost versions 11.7.x <= 11.7.0, 11.6.x <= 11.6.2, 11.5.x <= 11.5.5, 10.11.x <= 10.11.17 Fail to validate channel o...	2026-06-22
CVE-2026-6673	🔶 medium	6.4	0.2	Mattermost versions 11.7.x <= 11.7.0, 11.6.x <= 11.6.2, 11.5.x <= 11.5.5, 10.11.x <= 10.11.17 fail to authenticate Atlas...	2026-06-22
CVE-2026-8074	ℹ️ low	3.8	0.2	Mattermost versions 11.7.x <= 11.7.0, 10.11.x <= 10.11.17 fail to enforce bot-specific permission checks on the user act...	2026-06-22
CVE-2026-9162	🔶 medium	4.3	0.2	Mattermost versions 11.7.x <= 11.7.0, 11.6.x <= 11.6.2, 11.5.x <= 11.5.5, 10.11.x <= 10.11.17 fail to invalidate cached ...	2026-06-22
CVE-2026-3433	🔶 medium	4.3	0.2	Mattermost versions 11.6.x <= 11.6.1, 11.5.x <= 11.5.4, 10.11.x <= 10.11.15, 10.11.x <= 10.11.16 fail to restrict role_u...	2026-06-12

These CVEs affect the same products