medium4.3
CVE-2026-6340
Mattermost versions 11.5.x <= 11.5.1, 10.11.x <= 10.11.13, 11.4.x <= 11.4.3 fail to validate 7zip archive structure before processing which allows an authentic…
Impact
Mattermost versions 11.5.x <= 11.5.1, 10.11.x <= 10.11.13, 11.4.x <= 11.4.3 fail to validate 7zip archive structure before processing which allows an authenticated attacker to cause server memory exhaustion and denial of service via uploading a specially crafted 7zip file with excessive folder declarations.. Mattermost Advisory ID: MMSA-2026-00573
Affected packages
| Ecosystem | Package | Affected | Fixed in |
|---|---|---|---|
| go | github.com/mattermost/mattermost/server/v8 | >= 11.5.0, < 11.5.2 | 11.5.2 |
| go | github.com/mattermost/mattermost-server | < 5.3.2-0.20260325191733-fb11968f8798 | 5.3.2-0.20260325191733-fb11968f8798 |
Affected products
| Vendor | Product | Affected versions |
|---|---|---|
| Mattermost | Mattermost Server | from 10.11.0 before 10.11.14 from 11.4.0 before 11.4.4 from 11.5.0 before 11.5.2 |