{"id":"CVE-2026-2457","aliases":["GHSA-ph22-fw5m-w2q9","GO-2026-4732"],"url":"https://o3.security/vulnerability/CVE-2026-2457","summary":"WebSocket Message Spoofing via Permalink Embed Manipulation","details":"Mattermost versions 11.3.x <= 11.3.0, 11.2.x <= 11.2.2, 10.11.x <= 10.11.10 fail to sanitize client-supplied post metadata which allows an authenticated attacker to spoof permalink embeds impersonating other users via crafted PUT requests to the post update API endpoint.. Mattermost Advisory ID: MMSA-2025-00569","published":"2026-03-16T11:20:25.335Z","modified":"2026-09-18T03:46:19.854957322Z","cvss":{"score":4.3,"severity":"MEDIUM","vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N"},"epss":null,"cisaKev":null,"exploitsKnown":0,"affectedPackages":[{"ecosystem":"Go","name":"github.com/mattermost/mattermost/server/v8","fixedVersion":"8.0.0-20260123211116-9efe617be8b8"},{"ecosystem":"Go","name":"github.com/mattermost/mattermost-server","fixedVersion":"5.3.2-0.20260123211116-9efe617be8b8"},{"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/9efe617be8b8f1d036e12721e8e73b69a543ed34","label":"mattermost/mattermost@9efe617"},"references":[{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/2xxx/CVE-2026-2457.json"},{"type":"ADVISORY","url":"https://mattermost.com/security-updates"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-2457"},{"type":"WEB","url":"https://github.com/mattermost/mattermost/commit/9efe617be8b8f1d036e12721e8e73b69a543ed34"},{"type":"PACKAGE","url":"https://github.com/mattermost/mattermost"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-09-18T03:46:19.854957322Z"}}