{"id":"CVE-2026-2578","aliases":["GHSA-3rhr-jr63-hwq5","GO-2026-4734"],"url":"https://o3.security/vulnerability/CVE-2026-2578","summary":"Information Disclosure via WebSocket Event When Deleting Unrevealed Burn on Read Posts","details":"Mattermost versions 11.3.x <= 11.3.0 fail to preserve the redacted state of burn-on-read posts during deletion which allows channel members to access unrevealed burn-on-read message contents via the WebSocket post deletion event.. Mattermost Advisory ID: MMSA-2026-00579","published":"2026-03-16T11:58:09.834Z","modified":"2026-08-12T03:51:22.527772038Z","cvss":{"score":4.3,"severity":"MEDIUM","vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N"},"epss":null,"cisaKev":null,"exploitsKnown":0,"affectedPackages":[{"ecosystem":"Go","name":"github.com/mattermost/mattermost/server/v8","fixedVersion":"8.0.0-20260127062706-c6b205f0d770"},{"ecosystem":"Go","name":"github.com/mattermost/mattermost-server","fixedVersion":"5.3.2-0.20260127062706-c6b205f0d770"},{"ecosystem":"Go","name":"github.com/mattermost/mattermost-server","fixedVersion":"10.11.11"},{"ecosystem":"Go","name":"github.com/mattermost/mattermost-server","fixedVersion":"11.2.3"},{"ecosystem":"Go","name":"github.com/mattermost/mattermost-server","fixedVersion":"11.3.1"}],"fix":{"url":"https://github.com/mattermost/mattermost/commit/c6b205f0d77080ef805783de0628b9526af7faec","label":"mattermost/mattermost@c6b205f"},"references":[{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/2xxx/CVE-2026-2578.json"},{"type":"ADVISORY","url":"https://mattermost.com/security-updates"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-2578"},{"type":"WEB","url":"https://github.com/mattermost/mattermost/commit/c6b205f0d77080ef805783de0628b9526af7faec"},{"type":"PACKAGE","url":"https://github.com/mattermost/mattermost"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-08-12T03:51:22.527772038Z"}}