{
  "containers": {
    "cna": {
      "affected": [
        {
          "product": "discourse",
          "vendor": "discourse",
          "versions": [
            {
              "status": "affected",
              "version": "\u003c 2026.1.6"
            },
            {
              "status": "affected",
              "version": "\u003e= 2026.5.0-latest, \u003c 2026.5.2"
            },
            {
              "status": "affected",
              "version": "\u003e= 2026.6.0-latest, \u003c 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\u0027s nonce-based Content Security Policy, resulting in arbitrary JavaScript execution in visitors\u0027 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 (\u0027Cross-site Scripting\u0027)",
              "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": "2026-08-17T15:30:17.691Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
    "nvd": "{\"cve\":{\"id\":\"CVE-2026-55674\",\"sourceIdentifier\":\"security-advisories@github.com\",\"published\":\"2026-08-17T16:16:58.917\",\"lastModified\":\"2026-08-17T16:16:58.917\",\"vulnStatus\":\"Received\",\"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\u0027s nonce-based Content Security Policy, resulting in arbitrary JavaScript execution in visitors\u0027 browsers. This issue is fixed in versions 2026.1.6, 2026.5.2, 2026.6.1, and 2026.7.0.\"}],\"affected\":[{\"source\":\"security-advisories@github.com\",\"affectedData\":[{\"vendor\":\"discourse\",\"product\":\"discourse\",\"versions\":[{\"version\":\"\u003c 2026.1.6\",\"status\":\"affected\"},{\"version\":\"\u003e= 2026.5.0-latest, \u003c 2026.5.2\",\"status\":\"affected\"},{\"version\":\"\u003e= 2026.6.0-latest, \u003c 2026.6.1\",\"status\":\"affected\"}]}]}],\"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}]},\"weaknesses\":[{\"source\":\"security-advisories@github.com\",\"type\":\"Primary\",\"description\":[{\"lang\":\"en\",\"value\":\"CWE-79\"}]}],\"references\":[{\"url\":\"https://github.com/discourse/discourse/security/advisories/GHSA-qx4v-rg4v-pm2g\",\"source\":\"security-advisories@github.com\"}]}}"
  }
}