{"id":"GHSA-vqp5-2mrp-qqxg","summary":"Mattermost doesn't validate the Host header when constructing response URLs for custom slash command","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":["CVE-2026-6333","GO-2026-5671"],"modified":"2026-06-25T23:11:47.382160615Z","published":"2026-05-18T09:31:48Z","database_specific":{"github_reviewed_at":"2026-06-01T15:29:47Z","nvd_published_at":"2026-05-18T09:16:23Z","cwe_ids":["CWE-918"],"severity":"LOW","github_reviewed":true},"references":[{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-6333"},{"type":"WEB","url":"https://github.com/mattermost/mattermost/commit/e738016c592045e14bf926eafaeda6f8521def6d"},{"type":"PACKAGE","url":"https://github.com/mattermost/mattermost"},{"type":"WEB","url":"https://mattermost.com/security-updates"}],"affected":[{"package":{"name":"github.com/mattermost/mattermost/server/v8","ecosystem":"Go","purl":"pkg:golang/github.com/mattermost/mattermost/server/v8"},"ranges":[{"type":"SEMVER","events":[{"introduced":"11.5.0"},{"fixed":"11.5.2"}]}],"database_specific":{"source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/05/GHSA-vqp5-2mrp-qqxg/GHSA-vqp5-2mrp-qqxg.json"}},{"package":{"name":"github.com/mattermost/mattermost/server/v8","ecosystem":"Go","purl":"pkg:golang/github.com/mattermost/mattermost/server/v8"},"ranges":[{"type":"SEMVER","events":[{"introduced":"10.11.0"},{"fixed":"10.11.14"}]}],"database_specific":{"source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/05/GHSA-vqp5-2mrp-qqxg/GHSA-vqp5-2mrp-qqxg.json"}},{"package":{"name":"github.com/mattermost/mattermost/server/v8","ecosystem":"Go","purl":"pkg:golang/github.com/mattermost/mattermost/server/v8"},"ranges":[{"type":"SEMVER","events":[{"introduced":"0"},{"fixed":"8.0.0-20260325160634-e738016c5920"}]}],"database_specific":{"source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/05/GHSA-vqp5-2mrp-qqxg/GHSA-vqp5-2mrp-qqxg.json"}},{"package":{"name":"github.com/mattermost/mattermost-server","ecosystem":"Go","purl":"pkg:golang/github.com/mattermost/mattermost-server"},"ranges":[{"type":"SEMVER","events":[{"introduced":"0"},{"fixed":"5.3.2-0.20260325160634-e738016c5920"}]}],"database_specific":{"source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/05/GHSA-vqp5-2mrp-qqxg/GHSA-vqp5-2mrp-qqxg.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"}]}