How severe is CVE-2024-42406?

CVE-2024-42406 has a CVSS 3.x base score of 5.4, rated medium severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is low, integrity low, and availability none.

Is CVE-2024-42406 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (13th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2024-42406?

CVE-2024-42406 primarily affects Mattermost Mattermost Server. In total, 5 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2024-42406?

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

Does CVE-2024-42406 have an EU (EUVD) identifier?

Yes. CVE-2024-42406 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2024-39606.

When was CVE-2024-42406 published?

CVE-2024-42406 was published on 2024-09-26 and last updated on 2026-06-17.

CVE-2024-42406

CVE-2024-42406 is a medium-severity vulnerability in Mattermost Mattermost Server with a CVSS 3.x base score of 5.4. 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-284.

Key facts

Severity: Medium (CVSS 3.x base score 5.4)
EPSS exploit prediction: 0% (13th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2024-39606
Weakness: CWE-284
Affected product: Mattermost Mattermost Server
Published: 2024-09-26
Last modified: 2026-06-17

Description

Mattermost versions 9.11.x <= 9.11.0, 9.10.x <= 9.10.1, 9.9.x <= 9.9.2 and 9.5.x <= 9.5.8 fail to properly authorize requests when viewing archived channels is disabled, which allows an attacker to retrieve post and file information about archived channels. Examples are flagged or unread posts as well as files.

Frequently asked questions

What is CVE-2024-42406?: Mattermost versions 9.11.x <= 9.11.0, 9.10.x <= 9.10.1, 9.9.x <= 9.9.2 and 9.5.x <= 9.5.8 fail to properly authorize requests when viewing archived channels is disabled, which allows an attacker to retrieve post and file information about archived channels. Examples are flagged or unread posts as well as files.
How severe is CVE-2024-42406?: CVE-2024-42406 has a CVSS 3.x base score of 5.4, rated medium severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is low, integrity low, and availability none.
Is CVE-2024-42406 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (13th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2024-42406?: CVE-2024-42406 primarily affects Mattermost Mattermost Server. In total, 5 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2024-42406?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
Does CVE-2024-42406 have an EU (EUVD) identifier?: Yes. CVE-2024-42406 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2024-39606.
When was CVE-2024-42406 published?: CVE-2024-42406 was published on 2024-09-26 and last updated on 2026-06-17.

References

https://mattermost.com/security-updates

Affected products (5)

cpe:2.3:a:mattermost:mattermost_server:*:*:*:*:*:*:*:*
cpe:2.3:a:mattermost:mattermost_server:9.11.0:-:*:*:*:*:*:*
cpe:2.3:a:mattermost:mattermost_server:9.11.0:rc1:*:*:*:*:*:*
cpe:2.3:a:mattermost:mattermost_server:9.11.0:rc2:*:*:*:*:*:*
cpe:2.3:a:mattermost:mattermost_server:9.11.0:rc3:*:*:*:*:*:*

More vulnerabilities in Mattermost Mattermost Server

CVE-2025-12421 — Critical (CVSS 9.9): Mattermost versions 11.0.x <= 11.0.2, 10.12.x <= 10.12.1, 10.11.x <= 10.11.4, 10.5.x <= 10.5.12 fail to to verify that…
CVE-2025-12419 — Critical (CVSS 9.9): Mattermost versions 10.12.x <= 10.12.1, 10.11.x <= 10.11.4, 10.5.x <= 10.5.12, 11.0.x <= 11.0.3 fail to properly…
CVE-2025-4981 — Critical (CVSS 9.9): Mattermost versions 10.5.x <= 10.5.5, 9.11.x <= 9.11.15, 10.8.x <= 10.8.0, 10.7.x <= 10.7.2, 10.6.x <= 10.6.5 fail to…
CVE-2025-25279 — Critical (CVSS 9.9): Mattermost versions 10.4.x <= 10.4.1, 9.11.x <= 9.11.7, 10.3.x <= 10.3.2, 10.2.x <= 10.2.2 fail to properly validate…
CVE-2025-20051 — Critical (CVSS 9.9): Mattermost versions 10.4.x <= 10.4.1, 9.11.x <= 9.11.7, 10.3.x <= 10.3.2, 10.2.x <= 10.2.2 fail to properly validate…
CVE-2017-18920 — Critical (CVSS 9.8): An issue was discovered in Mattermost Server before 3.6.2. The WebSocket feature does not follow the Same Origin Policy.

All CVEs affecting Mattermost Mattermost Server →

Other CWE-284 (Improper Access Control) vulnerabilities

CVE-2026-50746 — Critical (CVSS 10.0): A malicious actor with access to the network could exploit an Improper Access Control vulnerability found in UniFi…
CVE-2026-46978 — Critical (CVSS 10.0): Vulnerability in the Oracle Solaris product of Oracle Systems (component: Remote Administration Daemon). The…
CVE-2026-35308 — Critical (CVSS 10.0): Vulnerability in the Oracle Coherence product of Oracle Fusion Middleware (component: Centralized Third Party Jars).…
CVE-2026-35307 — Critical (CVSS 10.0): Vulnerability in the Oracle Coherence product of Oracle Fusion Middleware (component: Core). Supported versions that…
CVE-2026-46695 — Critical (CVSS 10.0): Boxlite is a sandbox service that allows users to create lightweight virtual machines (Boxes) and launch OCI containers…
CVE-2026-46840 — Critical (CVSS 10.0): Vulnerability in Oracle REST Data Services (component: Backend-as-a-Service). Supported versions that are affected are…

Browse all CWE-284 (Improper Access Control) vulnerabilities →