{"id":"CVE-2025-20621","aliases":["GHSA-w6xh-c82w-h997","GO-2025-3407"],"url":"https://o3.security/vulnerability/CVE-2025-20621","summary":"Webapp crash via object that can't be cast to String in Attachment Field","details":"Mattermost versions 10.2.x <= 10.2.0, 9.11.x <= 9.11.5, 10.0.x <= 10.0.3, 10.1.x <= 10.1.3 fail to properly handle posts with attachments containing fields that cannot be cast to a String, which allows an attacker to cause the webapp to crash via creating and sending such a post to a channel.","published":"2025-01-16T18:16:28.042Z","modified":"2026-08-12T03:51:18.382000376Z","cvss":{"score":6.5,"severity":"MEDIUM","vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H"},"epss":null,"cisaKev":null,"exploitsKnown":0,"affectedPackages":[{"ecosystem":"Go","name":"github.com/mattermost/mattermost/server/v8","fixedVersion":"10.2.1"},{"ecosystem":"Go","name":"github.com/mattermost/mattermost/server/v8","fixedVersion":"10.1.4"},{"ecosystem":"Go","name":"github.com/mattermost/mattermost/server/v8","fixedVersion":"10.0.4"},{"ecosystem":"Go","name":"github.com/mattermost/mattermost/server/v8","fixedVersion":"9.11.6"},{"ecosystem":"Go","name":"github.com/mattermost/mattermost/server/v8","fixedVersion":"8.0.0-20241127161322-25ff7a3779a5"}],"fix":null,"references":[{"type":"WEB","url":"https://mattermost.com/security-updates"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2025/20xxx/CVE-2025-20621.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2025-20621"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-08-12T03:51:18.382000376Z"}}