{"id":"GHSA-xvcx-mgpc-5xh3","revision":"5d47f9f8379c418785ebf7b07cbe6819","records":[{"revision":"5d47f9f8379c418785ebf7b07cbe6819","observedAt":"2026-10-24T13:19:41.952+00:00","statement":{"source":"osv","id":"GHSA-xvcx-mgpc-5xh3","aliases":["CVE-2026-6339","GO-2026-5769"],"title":"Mattermost doesn't validate the X-Requested-With header on the burn-on-read reveal endpoint","description":"Mattermost versions 11.5.x <= 11.5.1, 11.4.x <= 11.4.3 fail to validate the X-Requested-With header on the burn-on-read reveal endpoint which allows an authenticated channel member to force the reveal of a burn-on-read message without recipient consent via a crafted Markdown image tag.. Mattermost Advisory ID: MMSA-2026-00636","state":0,"publishedAt":"2026-05-18T09:31:48+00:00","modifiedAt":"2026-06-25T23:11:08.5266315+00:00","affected":[{"ecosystem":"Go","name":"github.com/mattermost/mattermost/server/v8","ranges":[{"type":"SEMVER","events":[{"kind":"introduced","version":"11.5.0"},{"kind":"fixed","version":"11.5.2"}]}],"versions":[],"rawVersionEvidence":null},{"ecosystem":"Go","name":"github.com/mattermost/mattermost/server/v8","ranges":[{"type":"SEMVER","events":[{"kind":"introduced","version":"11.4.0"},{"kind":"fixed","version":"11.4.4"}]}],"versions":[],"rawVersionEvidence":null},{"ecosystem":"Go","name":"github.com/mattermost/mattermost/server/v8","ranges":[{"type":"SEMVER","events":[{"kind":"introduced","version":"0"},{"kind":"fixed","version":"8.0.0-20260327001745-7a339a6438f5"}]}],"versions":[],"rawVersionEvidence":null},{"ecosystem":"Go","name":"github.com/mattermost/mattermost-server","ranges":[{"type":"SEMVER","events":[{"kind":"introduced","version":"0"},{"kind":"fixed","version":"5.3.2-0.20260327001745-7a339a6438f5"}]}],"versions":[],"rawVersionEvidence":null}],"metrics":[{"system":"CVSS_V3","vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L","score":null,"severity":null},{"system":"Publisher rating","vector":null,"score":null,"severity":"MODERATE"}],"references":["https://nvd.nist.gov/vuln/detail/CVE-2026-6339","https://github.com/mattermost/mattermost/commit/7a339a6438f5a4a5feba6b8de887f17a1378b207","https://github.com/mattermost/mattermost","https://mattermost.com/security-updates"],"sourceUrl":"https://github.com/advisories/GHSA-xvcx-mgpc-5xh3","license":"GitHub Advisory Database · CC-BY-4.0","key":"osv:GHSA-xvcx-mgpc-5xh3","identifiers":["GHSA-xvcx-mgpc-5xh3","CVE-2026-6339","GO-2026-5769"]},"retained":false,"historicalAffected":[]}],"coverage":[]}