{"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": "2026-08-17T15:30:17.691Z"}, "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"}}}}

{}

{"affected": [{"affectedData": [{"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"}]}], "source": "security-advisories@github.com"}], "cveTags": [], "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."}], "id": "CVE-2026-55674", "lastModified": "2026-08-17T16:16:58.917", "metrics": {"cvssMetricV31": [{"cvssData": {"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"}, "exploitabilityScore": 2.8, "impactScore": 5.8, "source": "security-advisories@github.com", "type": "Secondary"}]}, "published": "2026-08-17T16:16:58.917", "references": [{"source": "security-advisories@github.com", "url": "https://github.com/discourse/discourse/security/advisories/GHSA-qx4v-rg4v-pm2g"}], "sourceIdentifier": "security-advisories@github.com", "vulnStatus": "Received", "weaknesses": [{"description": [{"lang": "en", "value": "CWE-79"}], "source": "security-advisories@github.com", "type": "Primary"}]}

{}

{"affected": [{"configurations": [{"platform": null, "status": "affected", "versions": {"scheme": "semver", "value": "[0,2026.1.6)"}}, {"platform": null, "status": "affected", "versions": {"scheme": "semver", "value": "[2026.5.0-latest,2026.5.2)"}}, {"platform": null, "status": "affected", "versions": {"scheme": "semver", "value": "[2026.6.0-latest,2026.6.1)"}}], "enrichment": {"confidence": 100.0, "confidence_source": "matching", "scores": [{"score": 100.0, "source": "matching"}]}, "original": {"product": "discourse", "source": "cna", "vendor": "discourse"}, "product": "discourse", "vendor": "discourse"}], "created": "2026-08-17T16:30:06.585626+00:00", "updated": "2026-08-17T16:30:06.585649+00:00", "vendors": ["discourse", "discourse$PRODUCT$discourse"]}