{"schema_version":"1.7.5","id":"GHSA-34g8-9fpp-46ch","published":"2026-03-16T15:30:43Z","modified":"2026-03-26T21:11:03.241919Z","aliases":["CVE-2026-2456","GO-2026-4726"],"summary":"Mattermost fails to limit the size of responses from integration action endpoints","details":"Mattermost versions 11.3.x <= 11.3.0, 11.2.x <= 11.2.2, 10.11.x <= 10.11.10 Mattermost fails to limit the size of responses from integration action endpoints, which allows an authenticated attacker to cause server memory exhaustion and denial of service via a malicious integration server that returns an arbitrarily large response when a user clicks an interactive message button. Mattermost Advisory ID: MMSA-2026-00571","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":"0"},{"fixed":"8.0.0-20260127165411-fe3052073dc6"}]}],"database_specific":{"source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/03/GHSA-34g8-9fpp-46ch/GHSA-34g8-9fpp-46ch.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":"5.3.2-0.20260127165411-fe3052073dc6"}]}],"database_specific":{"source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/03/GHSA-34g8-9fpp-46ch/GHSA-34g8-9fpp-46ch.json"}},{"package":{"name":"github.com/mattermost/mattermost-server","ecosystem":"Go","purl":"pkg:golang/github.com/mattermost/mattermost-server"},"ranges":[{"type":"SEMVER","events":[{"introduced":"10.11.0-rc1"},{"fixed":"10.11.11"}]}],"database_specific":{"source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/03/GHSA-34g8-9fpp-46ch/GHSA-34g8-9fpp-46ch.json"}},{"package":{"name":"github.com/mattermost/mattermost-server","ecosystem":"Go","purl":"pkg:golang/github.com/mattermost/mattermost-server"},"ranges":[{"type":"SEMVER","events":[{"introduced":"11.2.0-rc1"},{"fixed":"11.2.3"}]}],"database_specific":{"source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/03/GHSA-34g8-9fpp-46ch/GHSA-34g8-9fpp-46ch.json"}},{"package":{"name":"github.com/mattermost/mattermost-server","ecosystem":"Go","purl":"pkg:golang/github.com/mattermost/mattermost-server"},"ranges":[{"type":"SEMVER","events":[{"introduced":"11.3.0-rc1"},{"fixed":"11.3.1"}]}],"database_specific":{"source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/03/GHSA-34g8-9fpp-46ch/GHSA-34g8-9fpp-46ch.json"}}],"references":[{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-2456"},{"type":"WEB","url":"https://github.com/mattermost/mattermost/commit/fe3052073dc67e3c920baf9fe7efd44ac1d8124c"},{"type":"PACKAGE","url":"https://github.com/mattermost/mattermost"},{"type":"WEB","url":"https://mattermost.com/security-updates"}],"database_specific":{"cwe_ids":["CWE-789"],"github_reviewed":true,"github_reviewed_at":"2026-03-17T20:01:22Z","nvd_published_at":"2026-03-16T14:19:29Z","severity":"MODERATE"},"severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:N/I:N/A:H"}]}