{"cve":"CVE-2025-20621","nvd":{"published":"2025-01-16T19:15:29.960","modified":"2026-06-17T08:41:41.097","status":"Analyzed","description":"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.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","score":7.5},"cwes":["CWE-1287"],"references":["https://mattermost.com/security-updates"],"products":["mattermost:mattermost_server"],"source":"nvd","synced_at":"2026-10-19T21:58:20.756570362+00:00"},"epss":{"cve":"CVE-2025-20621","score":0.00478,"percentile":0.41319,"date":"2026-10-31"},"kev":null,"osv":[{"id":"GHSA-w6xh-c82w-h997","url":"https://osv.dev/vulnerability/GHSA-w6xh-c82w-h997","summary":"Mattermost webapp crash via a crafted post","modified":"2026-09-10T03:50:22.300964271Z","packages":[{"ecosystem":"Go","name":"github.com/mattermost/mattermost/server/v8","purl":"pkg:golang/github.com/mattermost/mattermost/server/v8","ranges":[">=10.2.0 <10.2.1"],"fixed":["10.2.1"]},{"ecosystem":"Go","name":"github.com/mattermost/mattermost/server/v8","purl":"pkg:golang/github.com/mattermost/mattermost/server/v8","ranges":[">=10.1.0 <10.1.4"],"fixed":["10.1.4"]},{"ecosystem":"Go","name":"github.com/mattermost/mattermost/server/v8","purl":"pkg:golang/github.com/mattermost/mattermost/server/v8","ranges":[">=10.0.0 <10.0.4"],"fixed":["10.0.4"]},{"ecosystem":"Go","name":"github.com/mattermost/mattermost/server/v8","purl":"pkg:golang/github.com/mattermost/mattermost/server/v8","ranges":[">=9.11.0 <9.11.6"],"fixed":["9.11.6"]},{"ecosystem":"Go","name":"github.com/mattermost/mattermost/server/v8","purl":"pkg:golang/github.com/mattermost/mattermost/server/v8","ranges":["<8.0.0-20241127161322-25ff7a3779a5"],"fixed":["8.0.0-20241127161322-25ff7a3779a5"]}]},{"id":"GO-2025-3407","url":"https://osv.dev/vulnerability/GO-2025-3407","summary":"Mattermost webapp crash via a crafted post in github.com/mattermost/mattermost-server","modified":"2026-02-04T02:47:10.000803Z","packages":[{"ecosystem":"Go","name":"github.com/mattermost/mattermost-server","purl":"pkg:golang/github.com/mattermost/mattermost-server","ranges":[">=9.11.0+incompatible <9.11.6+incompatible",">=10.0.0+incompatible <10.0.4+incompatible",">=10.1.0+incompatible <10.1.4+incompatible",">=10.2.0+incompatible <10.2.1+incompatible"],"fixed":["9.11.6+incompatible","10.0.4+incompatible","10.1.4+incompatible","10.2.1+incompatible"]},{"ecosystem":"Go","name":"github.com/mattermost/mattermost-server/v5","purl":"pkg:golang/github.com/mattermost/mattermost-server/v5","ranges":["all versions"],"fixed":[]},{"ecosystem":"Go","name":"github.com/mattermost/mattermost-server/v6","purl":"pkg:golang/github.com/mattermost/mattermost-server/v6","ranges":["all versions"],"fixed":[]},{"ecosystem":"Go","name":"github.com/mattermost/mattermost/server/v8","purl":"pkg:golang/github.com/mattermost/mattermost/server/v8","ranges":["<8.0.0-20241127161322-25ff7a3779a5"],"fixed":["8.0.0-20241127161322-25ff7a3779a5"]}]}],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}