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 colorschemeid (or darkschemeid) 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.
{
"cna_assigner": "GitHub_M",
"cwe_ids": [
"CWE-79"
],
"osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/55xxx/CVE-2026-55674.json"
}{
"extracted_events": [
{
"introduced": "0"
},
{
"fixed": "2026.1.6"
},
{
"introduced": "2026.5.0-latest"
},
{
"fixed": "2026.5.2"
},
{
"introduced": "2026.6.0-latest"
},
{
"fixed": "2026.6.1"
}
],
"source": "AFFECTED_FIELD"
}