How severe is CVE-2026-6062?

CVE-2026-6062 has a CVSS 3.x base score of 6.4, rated medium severity. It is exploitable over network with high attack complexity, requires low privileges and no user interaction. Impact on confidentiality is high, integrity low, and availability low.

Is CVE-2026-6062 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-2026-6062?

CVE-2026-6062 affects Mattermost Mattermost Server. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-6062?

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

Does CVE-2026-6062 have an EU (EUVD) identifier?

Yes. CVE-2026-6062 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-38250.

When was CVE-2026-6062 published?

CVE-2026-6062 was published on 2026-06-22 and last updated on 2026-06-23.

CVE-2026-6062

CVE-2026-6062 is a medium-severity vulnerability in Mattermost Mattermost Server with a CVSS 3.x base score of 6.4. 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-639.

Key facts

Severity: Medium (CVSS 3.x base score 6.4)
EPSS exploit prediction: 0% (5th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-38250
Weakness: CWE-639
Affected product: Mattermost Mattermost Server
Published: 2026-06-22
Last modified: 2026-06-23

Description

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 ownership of an existing subscription before applying edits which allows an authenticated attacker to hijack subscriptions from channels they have no access to via a crafted PUT request to the subscription edit endpoint.. Mattermost Advisory ID: MMSA-2026-00650

Frequently asked questions

What is CVE-2026-6062?: 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 ownership of an existing subscription before applying edits which allows an authenticated attacker to hijack subscriptions from channels they have no access to via a crafted PUT request to the subscription edit endpoint.. Mattermost Advisory ID: MMSA-2026-00650
How severe is CVE-2026-6062?: CVE-2026-6062 has a CVSS 3.x base score of 6.4, rated medium severity. It is exploitable over network with high attack complexity, requires low privileges and no user interaction. Impact on confidentiality is high, integrity low, and availability low.
Is CVE-2026-6062 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-2026-6062?: CVE-2026-6062 affects Mattermost Mattermost Server. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-6062?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
Does CVE-2026-6062 have an EU (EUVD) identifier?: Yes. CVE-2026-6062 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-38250.
When was CVE-2026-6062 published?: CVE-2026-6062 was published on 2026-06-22 and last updated on 2026-06-23.

References

https://mattermost.com/security-updates

Affected products (1)

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

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