CVE-2023-40703 - CVE House
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Status published Medium CVE-2023-40703

Denial of Service via specially crafted block fields in Mattermost Boards

Vulnerability Description

Mattermost fails to properly limit the characters allowed in different fields of a block in Mattermost Boards allowing a attacker to consume excessive resources, possibly leading to Denial of Service, by patching the field of a block using a specially crafted string. 

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:

  • vultza (vultza)

References

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Affected Vendor

Affected Software

Mattermost
Vulnerable Versions:
0, 9.1.1, 9.0.2, 7.8.13, 8.1.4

Timeline

Official Publish: November 27th, 2023
Last Modified: June 3rd, 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:L

Weaknesses (CWE)

CWE-400

MITRE ATT&CK TTPs

T1499 Endpoint Denial of Service
Impact
T1498 Network Denial of Service
Impact