Is CVE-2026-8823 in the CISA KEV catalog?

No. CVE-2026-8823 is not currently on the CISA Known Exploited Vulnerabilities list.

What is the CVSS severity of CVE-2026-8823?

CVE-2026-8823 has a CVSS v3 base score of 3.8 (LOW).

What is the EPSS score for CVE-2026-8823?

CVE-2026-8823 has an EPSS score of 0.23% (14th percentile), estimating the probability of exploitation in the next 30 days.

How do I fix CVE-2026-8823?

Upgrade mattermost server to 11.7.1 or later.

CVE & CISA-KEV Catalog

CVE-2026-8823

LOW

3.8

CVSS v3

NVD

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

CWE-863Incorrect Authorization

How to fix

Remediation Available

mattermost serverNVD

Affected:>= 11.7.0, < 11.7.1Fixed in:11.7.1CVE-2026-8823derived from NVD

Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.

CVSS v3 Vector

Exploitability

Attack VectorNetwork

Attack ComplexityLow

Privileges RequiredHigh

User InteractionNone

ScopeUnchanged

Impact

ConfidentialityNone

IntegrityLow

AvailabilityLow

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

Exploit Intelligence

0.23%probability of exploitation in 30 days

14thpercentile

Low risk: more likely to be exploited than 14% of all known CVEs.

References

Vendor Advisory1

mattermost.com

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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-06-26.