{"action":"Upgrade github.com/mattermost/mattermost-server to 10.11.15 or later.","affected":[{"fixed":"11.6.1","introduced":"11.6.0"},{"fixed":"11.5.4","introduced":"11.5.0"},{"fixed":"11.4.5","introduced":"11.4.0"},{"fixed":"10.11.15","introduced":"10.11.0"}],"component":"github.com/mattermost/mattermost-server","cve_ids":["CVE-2026-4915"],"ecosystem":"Go","epss":0.00277,"exploited":false,"fixed_versions":["11.6.1","11.5.4","11.4.5","10.11.15"],"ghsa_id":"GHSA-5gmf-x7hg-97wf","id":"tcs_01M5KEYAQ8KP7V88GFZ8HGCYJM","modified_at":"2026-07-07T16:11:26.107537868Z","published_at":"2026-05-26T13:30:40Z","references":["https://osv.dev/vulnerability/GHSA-5gmf-x7hg-97wf","https://nvd.nist.gov/vuln/detail/CVE-2026-4915","https://github.com/mattermost/mattermost/commit/faa7d75b4ea041701e97948f8aa1332e3626a39a","https://github.com/mattermost/mattermost","https://mattermost.com/security-updates"],"severity":{"label":"medium","score":6.5},"sources":[{"source":"osv","source_id":"GHSA-5gmf-x7hg-97wf","url":"https://osv.dev/vulnerability/GHSA-5gmf-x7hg-97wf"}],"summary":"Mattermost doesn't filter nil elements from outgoing webhook attachment payloads before processing"}