How severe is CVE-2026-26230?

CVE-2026-26230 has a CVSS 3.x base score of 3.8, rated low severity. It is exploitable over network with low attack complexity, requires high privileges and no user interaction. Impact on confidentiality is low, integrity low, and availability none.

Is CVE-2026-26230 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (5th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-26230?

CVE-2026-26230 affects Mattermost Mattermost Server. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-26230?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

Does CVE-2026-26230 have an EU (EUVD) identifier?

Yes. CVE-2026-26230 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-12518.

When was CVE-2026-26230 published?

CVE-2026-26230 was published on 2026-03-16 and last updated on 2026-06-17.

CVE-2026-26230

CVE-2026-26230 is a low-severity vulnerability in Mattermost Mattermost Server with a CVSS 3.x base score of 3.8. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-863.

Key facts

Severity: Low (CVSS 3.x base score 3.8)
EPSS exploit prediction: 0% (5th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-12518
Weakness: CWE-863
Affected product: Mattermost Mattermost Server
Published: 2026-03-16
Last modified: 2026-06-17

Description

Mattermost versions 10.11.x <= 10.11.10 fail to properly validate permission requirements in the team member roles API endpoint which allows team administrators to demote members to guest role. Mattermost Advisory ID: MMSA-2025-00531

Frequently asked questions

What is CVE-2026-26230?: Mattermost versions 10.11.x <= 10.11.10 fail to properly validate permission requirements in the team member roles API endpoint which allows team administrators to demote members to guest role. Mattermost Advisory ID: MMSA-2025-00531
How severe is CVE-2026-26230?: CVE-2026-26230 has a CVSS 3.x base score of 3.8, rated low severity. It is exploitable over network with low attack complexity, requires high privileges and no user interaction. Impact on confidentiality is low, integrity low, and availability none.
Is CVE-2026-26230 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (5th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-26230?: CVE-2026-26230 affects Mattermost Mattermost Server. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-26230?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
Does CVE-2026-26230 have an EU (EUVD) identifier?: Yes. CVE-2026-26230 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-12518.
When was CVE-2026-26230 published?: CVE-2026-26230 was published on 2026-03-16 and last updated on 2026-06-17.

References

https://mattermost.com/security-updates

Affected products (1)

cpe:2.3:a:mattermost:mattermost_server:*:*:*:*:*:*:*:*

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