CVE-2026-4915
published 2026-05-25CVE-2026-4915: 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…
medium6.5CVSS 3.1
AVNACLPRLUINSUCNINAH
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
Affected
8 ranges
| Vendor | Product | Version range | Fixed in |
|---|---|---|---|
| mattermost | mattermost | 10.11.0 – 10.11.14 | — |
| mattermost | mattermost | 11.4.0 – 11.4.4 | — |
| mattermost | mattermost | 11.5.0 – 11.5.3 | — |
| mattermost | mattermost | 11.6.0 – 11.6.0 | — |
| mattermost | mattermost_server | >= 10.11.0 < 10.11.15 | 10.11.15 |
| mattermost | mattermost_server | >= 11.4.0 < 11.4.5 | 11.4.5 |
| mattermost | mattermost_server | >= 11.5.0 < 11.5.4 | 11.5.4 |
| mattermost | mattermost_server | >= 11.6.0 < 11.6.1 | 11.6.1 |
CVSS provenance
nvdv3.16.5MEDIUMCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
cvelistv5v3.16.5MEDIUMCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H