How severe is CVE-2025-6226?

CVE-2025-6226 has a CVSS 3.x base score of 6.5, rated medium severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is high, integrity none, and availability none.

Is CVE-2025-6226 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (25th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2025-6226?

CVE-2025-6226 affects Mattermost Mattermost Server. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2025-6226?

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

Does CVE-2025-6226 have an EU (EUVD) identifier?

Yes. CVE-2025-6226 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2025-21867.

When was CVE-2025-6226 published?

CVE-2025-6226 was published on 2025-07-18 and last updated on 2026-06-17.

CVE-2025-6226

CVE-2025-6226 is a medium-severity vulnerability in Mattermost Mattermost Server with a CVSS 3.x base score of 6.5. 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-306.

Key facts

Severity: Medium (CVSS 3.x base score 6.5)
EPSS exploit prediction: 0% (25th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2025-21867
Weakness: CWE-306
Affected product: Mattermost Mattermost Server
Published: 2025-07-18
Last modified: 2026-06-17

Description

Mattermost versions 10.5.x <= 10.5.6, 10.8.x <= 10.8.1, 10.7.x <= 10.7.3, 9.11.x <= 9.11.16 fail to verify authorization when retrieving cached posts by PendingPostID which allows an authenticated user to read posts in private channels they don't have access to via guessing the PendingPostID of recently created posts.

Frequently asked questions

What is CVE-2025-6226?: Mattermost versions 10.5.x <= 10.5.6, 10.8.x <= 10.8.1, 10.7.x <= 10.7.3, 9.11.x <= 9.11.16 fail to verify authorization when retrieving cached posts by PendingPostID which allows an authenticated user to read posts in private channels they don't have access to via guessing the PendingPostID of recently created posts.
How severe is CVE-2025-6226?: CVE-2025-6226 has a CVSS 3.x base score of 6.5, rated medium severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is high, integrity none, and availability none.
Is CVE-2025-6226 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (25th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2025-6226?: CVE-2025-6226 affects Mattermost Mattermost Server. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2025-6226?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
Does CVE-2025-6226 have an EU (EUVD) identifier?: Yes. CVE-2025-6226 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2025-21867.
When was CVE-2025-6226 published?: CVE-2025-6226 was published on 2025-07-18 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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