Discourse: Cache poisoning/XSS via color scheme cookies
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.
BIT-discourse-2026-55674
Primary source · Revision 1
Imported from structured advisory data. Source references identify upstream records or fields; verify affected versions and your deployed configuration.
Security context
Source reference: osv:BIT-discourse-2026-55674
discourse
Source reference: /affected/0/package/name
- Affected versions
- Not stated in this record
- Fixed versions
- 2026.1.6
Source reference:
/affected/0/ranges2026.5.2Source reference:
/affected/0/ranges2026.6.1Source reference:
/affected/0/ranges - Prerequisites
- Not stated in this record
Structured affected-version data
Original package identities and version rules from this source.
[
{
"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"
}
]
}
],
"package": {
"name": "discourse",
"purl": "pkg:bitnami/discourse",
"ecosystem": "Bitnami"
},
"severity": [
{
"type": "CVSS_V3",
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:N"
}
],
"database_specific": {
"source": "https://github.com/bitnami/vulndb/tree/main/data/discourse/BIT-discourse-2026-55674.json"
}
}
]- Related CVEs
- CVE-2026-55674
Source reference:
/aliases
Publisher severity
critical
Source reference: /database_specific/severity
- Event
- #84151 · Revision 1
- Added to Heist Feed
- Publisher date