{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2026-55674", "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa", "state": "PUBLISHED", "assignerShortName": "GitHub_M", "dateReserved": "2026-06-17T00:05:03.778Z", "datePublished": "2026-08-17T15:30:17.691Z", "dateUpdated": "2026-08-18T14:43:21.430Z" }, "containers": { "cna": { "title": "Discourse: Cache poisoning/XSS via color scheme cookies", "problemTypes": [ { "descriptions": [ { "cweId": "CWE-79", "lang": "en", "description": "CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')", "type": "CWE" } ] } ], "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" } } ], "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" } ], "affected": [ { "vendor": "discourse", "product": "discourse", "versions": [ { "version": "< 2026.1.6", "status": "affected" }, { "version": ">= 2026.5.0-latest, < 2026.5.2", "status": "affected" }, { "version": ">= 2026.6.0-latest, < 2026.6.1", "status": "affected" } ] } ], "providerMetadata": { "orgId": "a0819718-46f1-4df5-94e2-005712e83aaa", "shortName": "GitHub_M", "dateUpdated": "2026-08-17T15:30:17.691Z" }, "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." } ], "source": { "advisory": "GHSA-qx4v-rg4v-pm2g", "discovery": "UNKNOWN" } }, "adp": [ { "metrics": [ { "other": { "type": "ssvc", "content": { "timestamp": "2026-08-18T14:42:55.146337Z", "id": "CVE-2026-55674", "options": [ { "Exploitation": "none" }, { "Automatable": "no" }, { "Technical Impact": "total" } ], "role": "CISA Coordinator", "version": "2.0.3" } } } ], "title": "CISA ADP Vulnrichment", "providerMetadata": { "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": "CISA-ADP", "dateUpdated": "2026-08-18T14:43:21.430Z" } } ] } }