CVE-2026-2455

published 2026-03-16

CVE-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…

Priority P4 23 medium 4.3 CVSS 3.1

AV N AC L PR L UI N S U C L I N A N

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

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CWE-918