CVEvulnerability

CVE-2026-10556

5.3 MEDIUM Published 2026-09-14 Modified 2026-10-07 Official page ↗
Status
Analyzed
Published
2026-09-14
Last modified
2026-10-07
Assigner
[email protected]
CVSS 3.1 ([email protected])
5.3 MEDIUM — CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
Weaknesses
CWE-476, CWE-754

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 configurations

• mattermost mattermost server (>= 10.11.0 < 10.11.23) • mattermost mattermost server (>= 11.7.0 < 11.7.8) • mattermost mattermost server (>= 11.8.0 < 11.8.5) • mattermost mattermost server (>= 11.9.0 < 11.9.1)

Related

Weakness · CWE (2)

  • CWE-476 NULL Pointer Dereference weakness
  • CWE-754 Improper Check for Unusual or Exceptional Conditions weakness

References