{"id":"BIT-discourse-2026-55674","summary":"Discourse: Cache poisoning/XSS via color scheme cookies","details":"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.","aliases":["CVE-2026-55674","GHSA-qx4v-rg4v-pm2g"],"modified":"2026-08-21T12:10:31.397085016Z","published":"2026-08-21T11:26:39.921Z","database_specific":{"cpes":["cpe:2.3:a:discourse:discourse:*:*:*:*:stable:*:*:*","cpe:2.3:a:discourse:discourse:*:*:*:*:beta:*:*:*"],"severity":"Critical"},"references":[{"type":"WEB","url":"https://github.com/discourse/discourse/security/advisories/GHSA-qx4v-rg4v-pm2g"},{"type":"WEB","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-55674"}],"affected":[{"package":{"name":"discourse","ecosystem":"Bitnami","purl":"pkg:bitnami/discourse"},"ranges":[{"type":"SEMVER","events":[{"introduced":"0"},{"fixed":"2026.1.6"},{"introduced":"2026.5.0"},{"fixed":"2026.5.2"},{"introduced":"2026.6.0"},{"fixed":"2026.6.1"}]}],"database_specific":{"source":"https://github.com/bitnami/vulndb/tree/main/data/discourse/BIT-discourse-2026-55674.json"},"severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:N"}]}],"schema_version":"1.9.0"}