{"api_version":"1","generated_at":"2026-08-24T11:52:26+00:00","cve":"CVE-2026-55674","urls":{"html":"https://cve.report/CVE-2026-55674","api":"https://cve.report/api/cve/CVE-2026-55674.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2026-55674","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-55674"},"summary":{"title":"Discourse: Cache poisoning/XSS via color scheme cookies","description":"Discourse is an open-source discussion platform. Prior to 2026.1.6, 2026.5.2, 2026.6.1, and 2026.7.0, an unauthenticated attacker could send a single request with a crafted color_scheme_id (or dark_scheme_id) cookie to inject arbitrary HTML into a Discourse page. Because the cookie value was rendered into a color scheme tag without escaping, the attacker could break out of the attribute and inject a tag that bypassed Discourse's nonce-based Content Security Policy, resulting in arbitrary JavaScript execution in visitors' browsers. This issue is fixed in versions 2026.1.6, 2026.5.2, 2026.6.1, and 2026.7.0.","state":"PUBLISHED","assigner":"GitHub_M","published_at":"2026-08-17 16:16:58","updated_at":"2026-08-18 15:16:55"},"problem_types":["CWE-79","CWE-79 CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')"],"metrics":[{"version":"3.1","source":"security-advisories@github.com","type":"Secondary","score":"9.3","severity":"CRITICAL","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:N","data":{"version":"3.1","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:N","baseScore":9.3,"baseSeverity":"CRITICAL","attackVector":"NETWORK","attackComplexity":"LOW","privilegesRequired":"NONE","userInteraction":"REQUIRED","scope":"CHANGED","confidentialityImpact":"HIGH","integrityImpact":"HIGH","availabilityImpact":"NONE"}},{"version":"3.1","source":"CNA","type":"DECLARED","score":"9.3","severity":"CRITICAL","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:N","data":{"attackComplexity":"LOW","attackVector":"NETWORK","availabilityImpact":"NONE","baseScore":9.3,"baseSeverity":"CRITICAL","confidentialityImpact":"HIGH","integrityImpact":"HIGH","privilegesRequired":"NONE","scope":"CHANGED","userInteraction":"REQUIRED","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:N","version":"3.1"}}],"references":[{"url":"https://github.com/discourse/discourse/security/advisories/GHSA-qx4v-rg4v-pm2g","name":"https://github.com/discourse/discourse/security/advisories/GHSA-qx4v-rg4v-pm2g","refsource":"security-advisories@github.com","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-55674","name":"CVE Program record","refsource":"CVE.ORG","tags":["canonical"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-55674","name":"NVD vulnerability detail","refsource":"NVD","tags":["canonical","analysis"]}],"affected":[{"source":"CNA","vendor":"discourse","product":"discourse","version":"affected < 2026.1.6","platforms":[]},{"source":"CNA","vendor":"discourse","product":"discourse","version":"affected >= 2026.5.0-latest, < 2026.5.2","platforms":[]},{"source":"CNA","vendor":"discourse","product":"discourse","version":"affected >= 2026.6.0-latest, < 2026.6.1","platforms":[]}],"timeline":[],"solutions":[],"workarounds":[],"exploits":[],"credits":[],"nvd_cpes":[],"vendor_comments":[],"enrichments":{"kev":null,"epss":{"cve_year":"2026","cve_id":"55674","cve":"CVE-2026-55674","epss":"0.003370000","percentile":"0.265980000","score_date":"2026-08-18","updated_at":"2026-08-19 00:07:28"},"legacy_qids":[]},"source_records":{"cve_program":{"containers":{"adp":[{"metrics":[{"other":{"content":{"id":"CVE-2026-55674","options":[{"Exploitation":"none"},{"Automatable":"no"},{"Technical Impact":"total"}],"role":"CISA Coordinator","timestamp":"2026-08-18T14:42:55.146337Z","version":"2.0.3"},"type":"ssvc"}}],"providerMetadata":{"dateUpdated":"2026-08-18T14:43:21.430Z","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","shortName":"CISA-ADP"},"title":"CISA ADP Vulnrichment"}],"cna":{"affected":[{"product":"discourse","vendor":"discourse","versions":[{"status":"affected","version":"< 2026.1.6"},{"status":"affected","version":">= 2026.5.0-latest, < 2026.5.2"},{"status":"affected","version":">= 2026.6.0-latest, < 2026.6.1"}]}],"descriptions":[{"lang":"en","value":"Discourse is an open-source discussion platform. Prior to 2026.1.6, 2026.5.2, 2026.6.1, and 2026.7.0, an unauthenticated attacker could send a single request with a crafted color_scheme_id (or dark_scheme_id) cookie to inject arbitrary HTML into a Discourse page. Because the cookie value was rendered into a color scheme tag without escaping, the attacker could break out of the attribute and inject a tag that bypassed Discourse's nonce-based Content Security Policy, resulting in arbitrary JavaScript execution in visitors' browsers. This issue is fixed in versions 2026.1.6, 2026.5.2, 2026.6.1, and 2026.7.0."}],"metrics":[{"cvssV3_1":{"attackComplexity":"LOW","attackVector":"NETWORK","availabilityImpact":"NONE","baseScore":9.3,"baseSeverity":"CRITICAL","confidentialityImpact":"HIGH","integrityImpact":"HIGH","privilegesRequired":"NONE","scope":"CHANGED","userInteraction":"REQUIRED","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:N","version":"3.1"}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-79","description":"CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')","lang":"en","type":"CWE"}]}],"providerMetadata":{"dateUpdated":"2026-08-17T15:30:17.691Z","orgId":"a0819718-46f1-4df5-94e2-005712e83aaa","shortName":"GitHub_M"},"references":[{"name":"https://github.com/discourse/discourse/security/advisories/GHSA-qx4v-rg4v-pm2g","tags":["x_refsource_CONFIRM"],"url":"https://github.com/discourse/discourse/security/advisories/GHSA-qx4v-rg4v-pm2g"}],"source":{"advisory":"GHSA-qx4v-rg4v-pm2g","discovery":"UNKNOWN"},"title":"Discourse: Cache poisoning/XSS via color scheme cookies"}},"cveMetadata":{"assignerOrgId":"a0819718-46f1-4df5-94e2-005712e83aaa","assignerShortName":"GitHub_M","cveId":"CVE-2026-55674","datePublished":"2026-08-17T15:30:17.691Z","dateReserved":"2026-06-17T00:05:03.778Z","dateUpdated":"2026-08-18T14:43:21.430Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"},"nvd":{"publishedDate":"2026-08-17 16:16:58","lastModifiedDate":"2026-08-18 15:16:55","problem_types":["CWE-79","CWE-79 CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')"],"metrics":{"cvssMetricV31":[{"source":"security-advisories@github.com","type":"Secondary","cvssData":{"version":"3.1","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:N","baseScore":9.3,"baseSeverity":"CRITICAL","attackVector":"NETWORK","attackComplexity":"LOW","privilegesRequired":"NONE","userInteraction":"REQUIRED","scope":"CHANGED","confidentialityImpact":"HIGH","integrityImpact":"HIGH","availabilityImpact":"NONE"},"exploitabilityScore":2.8,"impactScore":5.8}],"ssvcV203":[{"source":"134c704f-9b21-4f2e-91b3-4a467353bcc0","ssvcData":{"timestamp":"2026-08-18T14:42:55.146337Z","id":"CVE-2026-55674","options":[{"exploitation":"none"},{"automatable":"no"},{"technicalImpact":"total"}],"role":"CISA Coordinator","version":"2.0.3"}}]},"configurations":[]},"legacy_mitre":{"record":{"CveYear":"2026","CveId":"55674","Ordinal":"1","Title":"Discourse: Cache poisoning/XSS via color scheme cookies","CVE":"CVE-2026-55674","Year":"2026"},"notes":[{"CveYear":"2026","CveId":"55674","Ordinal":"1","NoteData":"Discourse is an open-source discussion platform. Prior to 2026.1.6, 2026.5.2, 2026.6.1, and 2026.7.0, an unauthenticated attacker could send a single request with a crafted color_scheme_id (or dark_scheme_id) cookie to inject arbitrary HTML into a Discourse page. Because the cookie value was rendered into a color scheme tag without escaping, the attacker could break out of the attribute and inject a tag that bypassed Discourse's nonce-based Content Security Policy, resulting in arbitrary JavaScript execution in visitors' browsers. This issue is fixed in versions 2026.1.6, 2026.5.2, 2026.6.1, and 2026.7.0.","Type":"Description","Title":"Discourse: Cache poisoning/XSS via color scheme cookies"}]}}}