{"id":"CVE-2026-91121","revision":null,"records":[{"revision":"33321a2ace3f4aee8efe6fc4475ffc8b","observedAt":"2026-10-23T15:48:27.903+00:00","statement":{"source":"cve-program","id":"CVE-2026-91121","aliases":[],"title":"Discourse: Chat upload filenames rendered as raw HTML in excerpts","description":"Discourse is an open-source discussion platform. Prior to 2026.1.8, 2026.6.3, 2026.7.2, and 2026.8.0, attacker-controlled upload filenames used in chat message excerpts were rendered as unescaped HTML. A user able to upload a file and send chat content could place markup in a filename that was then interpreted by chat channel lists, chat summary emails, pinned message bars, reply previews, thread previews, and other excerpt renderers. The issue allowed trusted-HTML injection that altered rendered excerpt content, but JavaScript execution was not demonstrated with default Content Security Policy settings. The advisory states that no confidentiality, integrity, or availability impact was identified, while its structured scoring metadata separately assigns low integrity impact. Sites that disable or relax the default CSP have increased exposure. This issue is fixed in versions 2026.1.8, 2026.6.3, 2026.7.2, and 2026.8.0.","state":0,"publishedAt":"2026-09-24T17:05:20.53+00:00","modifiedAt":"2026-09-24T17:27:43.58+00:00","affected":[{"ecosystem":"Vendor product","name":"discourse","ranges":[],"versions":[],"rawVersionEvidence":"{\n                    \"vendor\": \"discourse\",\n                    \"product\": \"discourse\",\n                    \"versions\": [\n                        {\n                            \"version\": \"< 2026.8.0\",\n                            \"status\": \"affected\"\n                        },\n                        {\n                            \"version\": \">= 2026.7.0-latest, < 2026.7.2\",\n                            \"status\": \"affected\"\n                        },\n                        {\n                            \"version\": \">= 2026.6.0-latest, < 2026.6.3\",\n                            \"status\": \"affected\"\n                        },\n                        {\n                            \"version\": \">= 2026.1.0-latest, < 2026.1.8\",\n                            \"status\": \"affected\"\n                        }\n                    ]\n                }"}],"metrics":[{"system":"CVSS 3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:N/I:L/A:N","score":5,"severity":"MEDIUM"}],"references":["https://github.com/discourse/discourse/security/advisories/GHSA-34rh-wjfv-65gq","https://github.com/discourse/discourse/pull/42882","https://github.com/discourse/discourse/commit/24cd7cc4c868f20e6037d67d801d60c3e289b278","https://github.com/discourse/discourse/commit/6e7a181909c34a059d2b0a6291335a363205b787","https://github.com/discourse/discourse/commit/9d6f5e64a1cb68e8208520e4209b361e14f7394b","https://github.com/discourse/discourse/commit/af197941f7613a3845cba21d217641c77c8ef836"],"sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-91121","license":"CVE Program Terms of Use","key":"cve-program:CVE-2026-91121","identifiers":["CVE-2026-91121"]},"retained":false,"historicalAffected":[]}],"coverage":[{"source":"cisa-kev:global","scope":"Complete CISA KEV catalog; all vendors. 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Not a global EUVD catalog. Successful not-found lookups count as checked; they do not imply withdrawal or safety. No reader inventory is sent.","generation":"enrichment-0580dcc98aaa46a8935f8ff576f25037","complete":true,"records":13764,"lastAttemptAt":"2026-11-12T11:56:20.2141865+00:00","lastSuccessAt":"2026-11-12T11:56:20.209+00:00","error":null,"lastVerifiedAt":"2026-11-12T11:56:20.209+00:00","snapshotPublishedAt":null,"importing":false,"stagedRecords":0,"checkedIdentifiers":13817,"expectedIdentifiers":13817,"failedIdentifiers":0},{"source":"first-epss:nuget","scope":"FIRST EPSS for explicit CVE aliases in the collected public NuGet archive. Not a global EPSS backfill.","generation":"2026-11-12T11:55:28.1860721+00:00","complete":true,"records":1097,"lastAttemptAt":"2026-11-12T11:55:28.1860721+00:00","lastSuccessAt":"2026-11-12T11:55:28.4142299+00:00","error":null,"lastVerifiedAt":"2026-11-12T11:55:28.4142304+00:00","snapshotPublishedAt":null,"importing":false,"stagedRecords":0,"checkedIdentifiers":null,"expectedIdentifiers":null,"failedIdentifiers":null},{"source":"nvd","scope":"Rolling NVD lookups of CVE aliases in current public OSV archives; 500 identifiers per refresh, rechecked after 48 hours. Not a global NVD catalog. Successful not-found lookups count as checked; they do not imply withdrawal or safety. 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