CVE-2025-20621 - CVE House
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Status published Medium CVE-2025-20621

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

Vulnerability 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.

Impact Analysis

Refer to official advisory for detailed impact metrics.

Remediation

Ensure systems are updated to the latest vendor-supplied patch levels.

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Credits & Attribution

The following person or organization is credited with identifying this vulnerability, as recorded in the NVD database:

  • c0rydoras (c0rydoras)

References

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Affected Vendor

Affected Software

Mattermost
Vulnerable Versions:
10.2.0, 9.11.0, 10.0.0, 10.1.0, 10.3.0, 2.23.0, 10.2.1, 9.11.6, 10.0.4, 10.1.4

Timeline

Official Publish: January 16th, 2025
Last Modified: January 16th, 2025
Added to House: July 22nd, 2026

CVSS Vectors

V3: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Weaknesses (CWE)

CWE-1287

MITRE ATT&CK TTPs

No associated TTPs found for this vulnerability.