{"cve":"CVE-2026-6333","nvd":{"published":"2026-05-18T09:16:23.430","modified":"2026-10-14T20:10:00.190","status":"Analyzed","description":"Mattermost versions 11.5.x <= 11.5.1, 10.11.x <= 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","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:N/I:L/A:N","score":5.0},"cwes":["CWE-918"],"references":["https://mattermost.com/security-updates"],"products":["mattermost:mattermost_server"],"source":"nvd","synced_at":"2026-10-19T22:35:16.954578616+00:00"},"epss":{"cve":"CVE-2026-6333","score":0.00137,"percentile":0.03063,"date":"2026-10-25"},"kev":null,"osv":[{"id":"GHSA-vqp5-2mrp-qqxg","url":"https://osv.dev/vulnerability/GHSA-vqp5-2mrp-qqxg","summary":"Mattermost doesn't validate the Host header when constructing response URLs for custom slash command","modified":"2026-06-25T23:11:07.798838866Z","packages":[{"ecosystem":"Go","name":"github.com/mattermost/mattermost/server/v8","purl":"pkg:golang/github.com/mattermost/mattermost/server/v8","ranges":[">=11.5.0 <11.5.2"],"fixed":["11.5.2"]},{"ecosystem":"Go","name":"github.com/mattermost/mattermost/server/v8","purl":"pkg:golang/github.com/mattermost/mattermost/server/v8","ranges":[">=10.11.0 <10.11.14"],"fixed":["10.11.14"]},{"ecosystem":"Go","name":"github.com/mattermost/mattermost/server/v8","purl":"pkg:golang/github.com/mattermost/mattermost/server/v8","ranges":["<8.0.0-20260325160634-e738016c5920"],"fixed":["8.0.0-20260325160634-e738016c5920"]},{"ecosystem":"Go","name":"github.com/mattermost/mattermost-server","purl":"pkg:golang/github.com/mattermost/mattermost-server","ranges":["<5.3.2-0.20260325160634-e738016c5920"],"fixed":["5.3.2-0.20260325160634-e738016c5920"]}]},{"id":"GO-2026-5671","url":"https://osv.dev/vulnerability/GO-2026-5671","summary":"Mattermost doesn't validate the Host header when constructing response URLs for custom slash command in github.com/mattermost/mattermost-server","modified":"2026-06-25T23:01:38.693940001Z","packages":[{"ecosystem":"Go","name":"github.com/mattermost/mattermost-server","purl":"pkg:golang/github.com/mattermost/mattermost-server","ranges":[">=10.11.0+incompatible <10.11.14+incompatible",">=11.5.0+incompatible <11.5.2+incompatible"],"fixed":["10.11.14+incompatible","11.5.2+incompatible"]},{"ecosystem":"Go","name":"github.com/mattermost/mattermost-server/v5","purl":"pkg:golang/github.com/mattermost/mattermost-server/v5","ranges":["all versions"],"fixed":[]},{"ecosystem":"Go","name":"github.com/mattermost/mattermost-server/v6","purl":"pkg:golang/github.com/mattermost/mattermost-server/v6","ranges":["all versions"],"fixed":[]},{"ecosystem":"Go","name":"github.com/mattermost/mattermost/server/v8","purl":"pkg:golang/github.com/mattermost/mattermost/server/v8","ranges":["<8.0.0-20260325160634-e738016c5920"],"fixed":["8.0.0-20260325160634-e738016c5920"]}]}],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}