Description
Mattermost versions 11.6.x <= 11.6.5, 10.11.x <= 10.11.20, 11.8.x <= 11.8.1, 11.7.x <= 11.7.4 fail to limit the number of frames and enforce the file size cap on animated GIF uploads, which allows an authenticated attacker to cause a denial of service via a crafted animated GIF uploaded as a custom emoji.. Mattermost Advisory ID: MMSA-2026-00695
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| Mattermost | Mattermost | 11.6.0 – ≤ 11.6.5, 10.11.0 – ≤ 10.11.20, 11.8.0 – ≤ 11.8.1, 11.7.0 – ≤ 11.7.4 | 11.9.0 |
Advisories 1
- WID-SEC-2026-2107 Mattermost Server: Mehrere Schwachstellen BSI CERT-Bund (WID) · Jul 27, 2026
References
- MMSA-2026-00695 vendor-advisory