CVE-2026-2455
published 2026-03-16CVE-2026-2455: Mattermost versions 11.3.x <= 11.3.0, 11.2.x <= 11.2.2, 10.11.x <= 10.11.10 fail to canonicalize IPv4-mapped IPv6 addresses before reserved IP validation which…
medium4.3CVSS 3.1
AVNACLPRLUINSUCLINAN
Mattermost versions 11.3.x <= 11.3.0, 11.2.x <= 11.2.2, 10.11.x <= 10.11.10 fail to canonicalize IPv4-mapped IPv6 addresses before reserved IP validation which allows an attacker to perform SSRF attacks against internal services via IPv4-mapped IPv6 literals (e.g., [::ffff:127.0.0.1]).. Mattermost Advisory ID: MMSA-2026-00585
Affected
14 ranges
| Vendor | Product | Version range | Fixed in |
|---|---|---|---|
| github.com | mattermost_mattermost-server | >= 0 < 5.3.2-0.20260129133647-5d787969c2d5 | 5.3.2-0.20260129133647-5d787969c2d5 |
| github.com | mattermost_mattermost-server | >= 10.11.0-rc1 < 10.11.11 | 10.11.11 |
| github.com | mattermost_mattermost-server | >= 10.11.0-rc1+incompatible < 10.11.11+incompatible | 10.11.11+incompatible |
| github.com | mattermost_mattermost-server | >= 11.2.0-rc1 < 11.2.3 | 11.2.3 |
| github.com | mattermost_mattermost-server | >= 11.2.0-rc1+incompatible < 11.2.3+incompatible | 11.2.3+incompatible |
| github.com | mattermost_mattermost-server | >= 11.3.0-rc1 < 11.3.1 | 11.3.1 |
| github.com | mattermost_mattermost-server | >= 11.3.0-rc1+incompatible < 11.3.1+incompatible | 11.3.1+incompatible |
| github.com | mattermost_mattermost_server_v8 | >= 0 < 8.0.0-20260129133647-5d787969c2d5 | 8.0.0-20260129133647-5d787969c2d5 |
| mattermost | mattermost | 10.11.0 – 10.11.10 | — |
| mattermost | mattermost | 11.2.0 – 11.2.2 | — |
| mattermost | mattermost | 11.3.0 – 11.3.0 | — |
| mattermost | mattermost_server | >= 10.11.0 < 10.11.11 | 10.11.11 |
| mattermost | mattermost_server | >= 11.2.0 < 11.2.3 | 11.2.3 |
| mattermost | mattermost_server | >= 11.3.0 < 11.3.1 | 11.3.1 |