CVEvulnerability

CVE-2026-55674

9.3 CRITICAL Published 2026-08-17 Modified 2026-09-18 Official page ↗
Status
Deferred
Published
2026-08-17
Last modified
2026-09-18
Assigner
[email protected]
CVSS 3.1 ([email protected])
9.3 CRITICAL — CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:N
Weaknesses
CWE-79

Description

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.

Related

Weakness · CWE (1)

  • CWE-79 Improper Neutralization of Input During Web Page Generation weakness

References