CVE-2026-10556
5.3
Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
Exploitability: 3.9 / Impact: 1.4
Source: responsibledisclosure@mattermost.com (Secondary)
Description
Mattermost versions 11.9.x <= 11.9.0, 11.8.x <= 11.8.4, 11.7.x <= 11.7.7, 10.11.x <= 10.11.22 fail to validate null entries in Microsoft Graph webhook notification payloads, which allows an unauthenticated attacker to crash the Microsoft Calendar plugin process and deny calendar integration service to all users on the instance via a crafted {{POST}} request to the public webhook endpoint.. Mattermost Advisory ID: MMSA-2026-00693
Affected (4)
Products: Mattermost: Mattermost Server
Configuration A
| Vulnerable Software | Affected Versions |
|---|---|
| 10.11.0 ≤ version < 10.11.23 |
Related CWEs
CWE-476
NULL Pointer Dereference
The product dereferences a pointer that it expects to be valid but is NULL.
CWE-754
Improper Check for Unusual or Exceptional Conditions
The product does not check or incorrectly checks for unusual or exceptional conditions that are not expected to occur frequently during day to day operation of the product.
References (1)
Timeline
No history available yet.