{"cve":"CVE-2026-6046","nvd":{"published":"2026-06-12T17:16:26.957","modified":"2026-06-18T14:33:35.203","status":"Analyzed","description":"Mattermost versions 11.6.x <= 11.6.1, 11.5.x <= 11.5.4, 10.11.x <= 10.11.15, 10.11.x <= 10.11.16 fail to validate that a username returned during bot registration belongs to a bot account, which allows an unprivileged attacker to intercept private messages sent by plugins via direct message channels by pre-registering a user account with a predictable plugin bot username.. Mattermost Advisory ID: MMSA-2026-00649","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:N/A:N","score":5.3},"cwes":["CWE-200"],"references":["https://mattermost.com/security-updates"],"products":["mattermost:mattermost_server"],"source":"nvd","synced_at":"2026-10-19T22:38:48.522727527+00:00"},"epss":{"cve":"CVE-2026-6046","score":0.0019,"percentile":0.08687,"date":"2026-11-01"},"kev":null,"osv":[{"id":"GHSA-3vmp-whvv-5v9v","url":"https://osv.dev/vulnerability/GHSA-3vmp-whvv-5v9v","summary":"Mattermost doesn't validate that a username returned during bot registration belongs to a bot account","modified":"2026-09-10T03:50:55.370444496Z","packages":[{"ecosystem":"Go","name":"github.com/mattermost/mattermost-server","purl":"pkg:golang/github.com/mattermost/mattermost-server","ranges":[">=11.6.0 <11.6.1"],"fixed":["11.6.1"]},{"ecosystem":"Go","name":"github.com/mattermost/mattermost-server","purl":"pkg:golang/github.com/mattermost/mattermost-server","ranges":[">=11.5.0 <11.5.5"],"fixed":["11.5.5"]},{"ecosystem":"Go","name":"github.com/mattermost/mattermost-server","purl":"pkg:golang/github.com/mattermost/mattermost-server","ranges":[">=10.11.0 <10.11.17"],"fixed":["10.11.17"]},{"ecosystem":"Go","name":"github.com/mattermost/mattermost/server/v8","purl":"pkg:golang/github.com/mattermost/mattermost/server/v8","ranges":[">=8.0.0-20250731163400-5b955468ea1e <8.0.0-20260428151657-c79c3831061a"],"fixed":["8.0.0-20260428151657-c79c3831061a"]}]},{"id":"GO-2026-6279","url":"https://osv.dev/vulnerability/GO-2026-6279","summary":"Mattermost doesn't validate that a username returned during bot registration belongs to a bot account in github.com/mattermost/mattermost-server","modified":"2026-08-26T01:13:10.986219322Z","packages":[{"ecosystem":"Go","name":"github.com/mattermost/mattermost-server","purl":"pkg:golang/github.com/mattermost/mattermost-server","ranges":[">=10.11.0+incompatible <10.11.17+incompatible",">=11.5.0+incompatible <11.5.5+incompatible",">=11.6.0+incompatible <11.6.1+incompatible"],"fixed":["10.11.17+incompatible","11.5.5+incompatible","11.6.1+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":[">=8.0.0-20250731163400-5b955468ea1e <8.0.0-20260428151657-c79c3831061a"],"fixed":["8.0.0-20260428151657-c79c3831061a"]}]}],"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."]}