CVE-2025-20621

Webapp crash via object that can't be cast to String in Attachment Field

Published Jan 16, 2025 CVSS 3.1 · 6.5 Medium EPSS < 1% KEV · Not listed
Description
Mattermost versions 10.2.x <= 10.2.0, 9.11.x <= 9.11.5, 10.0.x <= 10.0.3, 10.1.x <= 10.1.3 fail to properly handle posts with attachments containing fields that cannot be cast to a String, which allows an attacker to cause the webapp to crash via creating and sending such a post to a channel.

Remediation

Vendor Solution

Update Mattermost to versions 10.3.0, 2.23.0, 10.2.1, 9.11.6, 10.0.4, 10.1.4 or higher.

Tracking

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Advisories

Source ID Title
EUVD EUVD EUVD-2025-0107 Mattermost versions 10.2.x <= 10.2.0, 9.11.x <= 9.11.5, 10.0.x <= 10.0.3, 10.1.x <= 10.1.3 fail to properly handle posts with attachments containing fields that cannot be cast to a String, which allows an attacker to cause the webapp to crash via creating and sending such a post to a channel.
Github GHSA Github GHSA GHSA-w6xh-c82w-h997 Mattermost webapp crash via a crafted post
References
History
Type Values Removed Values Added
First Time appeared Mattermost mattermost Server
CPEs cpe:2.3:a:mattermost:mattermost_server:*:*:*:*:*:*:*:*
cpe:2.3:a:mattermost:mattermost_server:10.2.0:-:*:*:*:*:*:*
Vendors & Products Mattermost mattermost Server
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Type Values Removed Values Added
Description Mattermost versions 10.2.x <= 10.2.0, 9.11.x <= 9.11.5, 10.0.x <= 10.0.3, 10.1.x <= 10.1.3 fail to properly handle posts with attachments containing fields that cannot be cast to a String, which allows an attacker to cause the webapp to crash via creating and sending such a post to a channel.
Title Webapp crash via object that can't be cast to String in Attachment Field
Weaknesses CWE-1287
References
Metrics cvssV3_1

{'score': 6.5, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
Mattermost
Published
Updated
Jan 16, 2025, 6:57 PM
Reserved
Jan 16, 2025, 6:10 PM
Status
Analyzed
Published
Jan 16, 2025, 7:15 PM
Modified
Jun 17, 2026, 8:41 AM