CVE-2026-4915
Server panic via outgoing webhook responses
CVSS Score
6.5
EPSS Score
0.0%
EPSS Percentile
12th
Mattermost versions 11.6.x <= 11.6.0, 11.5.x <= 11.5.3, 11.4.x <= 11.4.4, 10.11.x <= 10.11.14 fail to filter nil elements from outgoing webhook attachment payloads before processing, which allows an authenticated user to cause a denial of service (server process termination) via a crafted webhook callback response containing a null attachment entry.. Mattermost Advisory ID: MMSA-2026-00641
| CWE | CWE-754 |
| Vendor | mattermost |
| Product | mattermost |
| Published | May 25, 2026 |
| Last Updated | May 26, 2026 |
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CVSS v3 Breakdown
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H Attack Vector
Network
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High
Affected Versions
Mattermost / Mattermost
11.6.0 ≤ 11.6.0 11.5.0 ≤ 11.5.3 11.4.0 ≤ 11.4.4 10.11.0 ≤ 10.11.14
Credits
daw10