{"id":"CVE-2026-6333","summary":"SSRF via Host Header Spoofing in Custom Slash Commands","details":"Mattermost versions 11.5.x \u003c= 11.5.1, 10.11.x \u003c= 10.11.13 fail to validate the Host header when constructing response URLs for custom slash commands which allows an authenticated attacker to redirect slash command responses to an attacker-controlled server via a spoofed Host header.. Mattermost Advisory ID: MMSA-2026-00582","aliases":["GHSA-vqp5-2mrp-qqxg","GO-2026-5671"],"modified":"2026-08-12T03:51:45.305170917Z","published":"2026-05-18T08:41:29.342Z","related":["openSUSE-SU-2026:21483-1"],"database_specific":{"cna_assigner":"Mattermost","cwe_ids":["CWE-918"],"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/6xxx/CVE-2026-6333.json","unresolved_ranges":[{"source":"AFFECTED_FIELD","extracted_events":[{"introduced":"11.5.0"},{"last_affected":"11.5.1"},{"introduced":"10.11.0"},{"last_affected":"10.11.13"}]}]},"references":[{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/6xxx/CVE-2026-6333.json"},{"type":"ADVISORY","url":"https://mattermost.com/security-updates"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-6333"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/mattermost/mattermost","events":[{"introduced":"5b955468ea1ea8b56c0fb10feb258a36a767d7bb"},{"fixed":"b21ef302025ee100f04f358c16301dc75fea91d9"},{"introduced":"9f2616376582893035a7e3cb38b0fab648bba4e8"},{"fixed":"cc4ef6863ee114bc96be4e34478ec2f0db3eac4e"}],"database_specific":{"cpe":"cpe:2.3:a:mattermost:mattermost_server:*:*:*:*:*:*:*:*","extracted_events":[{"introduced":"10.11.0"},{"fixed":"10.11.14"},{"introduced":"11.5.0"},{"fixed":"11.5.2"}],"source":"CPE_RANGE"}}],"versions":["v10.11.14-rc1","v11.5.0","v11.5.2-rc2","v11.5.2-rc1","v10.11.13","v11.5.1","v10.11.13-rc1","v10.11.12","v10.11.11-rc2","v10.11.11","v10.11.11-rc1","v10.11.10","v10.11.9","v10.11.9-rc1","v10.11.8","v10.11.7","v10.11.6","v10.11.5","v10.11.4-rc3","v10.11.4","v10.11.4-rc2","v10.11.4-rc1","v10.11.3","v10.11.2-rc2","v10.11.2","v10.11.2-rc1","v10.11.1","v10.11.1-rc1","v10.11.0-rc3","v10.11.0","mattermost-redux@10.11.0","@mattermost/types@10.11.0","@mattermost/client@10.11.0"],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-6333.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:N/I:L/A:N"}]}