How severe is CVE-2025-55070?

CVE-2025-55070 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-2025-55070 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (19th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2025-55070?

CVE-2025-55070 affects Mattermost Mattermost Server. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2025-55070?

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

Does CVE-2025-55070 have an EU (EUVD) identifier?

Yes. CVE-2025-55070 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2025-186556.

When was CVE-2025-55070 published?

CVE-2025-55070 was published on 2025-11-14 and last updated on 2026-06-17.

CVE-2025-55070

Q: What is CVE-2025-55070?

Mattermost versions <11 fail to enforce multi-factor authentication on WebSocket connections which allows unauthenticated users to access sensitive information via WebSocket events

CVE-2025-55070 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% (19th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2025-186556
Weakness: CWE-306
Affected product: Mattermost Mattermost Server
Published: 2025-11-14
Last modified: 2026-06-17

Description

Mattermost versions <11 fail to enforce multi-factor authentication on WebSocket connections which allows unauthenticated users to access sensitive information via WebSocket events

Frequently asked questions

What is CVE-2025-55070?: Mattermost versions <11 fail to enforce multi-factor authentication on WebSocket connections which allows unauthenticated users to access sensitive information via WebSocket events
How severe is CVE-2025-55070?: CVE-2025-55070 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-2025-55070 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (19th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2025-55070?: CVE-2025-55070 affects Mattermost Mattermost Server. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2025-55070?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
Does CVE-2025-55070 have an EU (EUVD) identifier?: Yes. CVE-2025-55070 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2025-186556.
When was CVE-2025-55070 published?: CVE-2025-55070 was published on 2025-11-14 and last updated on 2026-06-17.

References

https://mattermost.com/security-updates

Affected products (1)

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

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-306 (Missing Authentication for Critical Function) vulnerabilities

CVE-2026-54309 — Critical (CVSS 10.0): n8n is an open source workflow automation platform. Prior to 2.25.7 and 2.26.2, when @n8n/mcp-browser is run in HTTP…
CVE-2026-50242 — Critical (CVSS 10.0): In JetBrains Hub before 2026.1.13757, 2025.3.148033, 2025.2.148048, 2025.1.148120, 2024.3.148430, 2024.2.148429…
CVE-2026-49257 — Critical (CVSS 10.0): mcp-pinot is a Python-based Model Context Protocol (MCP) server for interacting with Apache Pinot. In versions 3.0.1…
CVE-2026-46846 — Critical (CVSS 10.0): Vulnerability in the Oracle WebCenter Portal product of Oracle Fusion Middleware (component: Security Framework).…
CVE-2026-46803 — Critical (CVSS 10.0): Vulnerability in the Oracle WebCenter Portal product of Oracle Fusion Middleware (component: Security Framework).…
CVE-2026-46800 — Critical (CVSS 10.0): Vulnerability in the Oracle WebCenter Sites product of Oracle Fusion Middleware (component: WebCenter Sites).…

Browse all CWE-306 (Missing Authentication for Critical Function) vulnerabilities →