How severe is CVE-2025-20033?

CVE-2025-20033 has a CVSS 3.x base score of 4.3, rated medium severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability low.

Is CVE-2025-20033 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (44th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2025-20033?

CVE-2025-20033 affects Mattermost Mattermost Server. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2025-20033?

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

Does CVE-2025-20033 have an EU (EUVD) identifier?

Yes. CVE-2025-20033 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2025-0004.

When was CVE-2025-20033 published?

CVE-2025-20033 was published on 2025-01-09 and last updated on 2026-06-17.

CVE-2025-20033

CVE-2025-20033 is a medium-severity vulnerability in Mattermost Mattermost Server with a CVSS 3.x base score of 4.3. 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-1287.

Key facts

Severity: Medium (CVSS 3.x base score 4.3)
EPSS exploit prediction: 1% (44th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2025-0004
Weakness: CWE-1287
Affected product: Mattermost Mattermost Server
Published: 2025-01-09
Last modified: 2026-06-17

Description

Mattermost versions 10.2.0, 9.11.x <= 9.11.5, 10.0.x <= 10.0.3, 10.1.x <= 10.1.3 fail to properly validate post types, which allows attackers to deny service to users with the sysconsole_read_plugins permission via creating a post with the custom_pl_notification type and specific props.

Frequently asked questions

What is CVE-2025-20033?: Mattermost versions 10.2.0, 9.11.x <= 9.11.5, 10.0.x <= 10.0.3, 10.1.x <= 10.1.3 fail to properly validate post types, which allows attackers to deny service to users with the sysconsole_read_plugins permission via creating a post with the custom_pl_notification type and specific props.
How severe is CVE-2025-20033?: CVE-2025-20033 has a CVSS 3.x base score of 4.3, rated medium severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability low.
Is CVE-2025-20033 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (44th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2025-20033?: CVE-2025-20033 affects Mattermost Mattermost Server. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2025-20033?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
Does CVE-2025-20033 have an EU (EUVD) identifier?: Yes. CVE-2025-20033 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2025-0004.
When was CVE-2025-20033 published?: CVE-2025-20033 was published on 2025-01-09 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-1287 vulnerabilities

CVE-2024-51550 — Critical (CVSS 10.0): Data Validation / Data Sanitization vulnerabilities in Linux allows unvalidated and unsanitized data to be injected in…
CVE-2024-6298 — Critical (CVSS 10.0): Unauthorized file access in WEB Server in ABB ASPECT - Enterprise v3.08.01; NEXUS Series v3.08.01 ; MATRIX Series…
CVE-2026-44935 — Critical (CVSS 9.9): Missing validation of "valuesFrom" references in Helm Deployer of SUSE Rancher Fleet 0.15 before 0.15.2, 0.14 before…
CVE-2024-4879 — Critical (CVSS 9.8): ServiceNow has addressed an input validation vulnerability that was identified in Vancouver and Washington DC Now…
CVE-2021-32024 — Critical (CVSS 9.8): A remote code execution vulnerability in the BMP image codec of BlackBerry QNX SDP version(s) 6.4 to 7.1 could allow an…
CVE-2026-24307 — Critical (CVSS 9.3): Improper validation of specified type of input in M365 Copilot allows an unauthorized attacker to disclose information…

Browse all CWE-1287 vulnerabilities →