{"action":"Upgrade github.com/mattermost/mattermost-server to 5.3.2-0.20260129133647-5d787969c2d5 or later.","affected":[{"fixed":"5.3.2-0.20260129133647-5d787969c2d5","introduced":"0"},{"fixed":"10.11.11","introduced":"10.11.0-rc1"},{"fixed":"11.2.3","introduced":"11.2.0-rc1"},{"fixed":"11.3.1","introduced":"11.3.0-rc1"}],"component":"github.com/mattermost/mattermost-server","cve_ids":["CVE-2026-2455"],"ecosystem":"Go","epss":0.00168,"exploited":false,"fixed_versions":["5.3.2-0.20260129133647-5d787969c2d5","10.11.11","11.2.3","11.3.1"],"ghsa_id":"GHSA-gqv7-j2j8-qmwq","id":"tcs_01M5KFBA8P23M3HY8M08TQ34YA","modified_at":"2026-03-23T18:56:08.125706Z","published_at":"2026-03-16T15:30:47Z","references":["https://osv.dev/vulnerability/GHSA-gqv7-j2j8-qmwq","https://nvd.nist.gov/vuln/detail/CVE-2026-2455","https://github.com/mattermost/mattermost/commit/5d787969c2d5ab591a9dcd61b0810475eed7a646","https://github.com/mattermost/mattermost","https://mattermost.com/security-updates"],"severity":{"label":"medium","score":4.3},"sources":[{"source":"osv","source_id":"GHSA-gqv7-j2j8-qmwq#Go/github.com/mattermost/mattermost-server","url":"https://osv.dev/vulnerability/GHSA-gqv7-j2j8-qmwq"}],"summary":"Mattermost fails to canonicalize IPv4-mapped IPv6 addresses before reserved IP validation"}