CVE-2026-55674

Discourse: Cache poisoning/XSS via color scheme cookies

Published 17 Aug 2026Modified 18 Sep 2026CWE 79

In the Trivy database since at least 24 Oct 2026, 07:11 UTCWhen it arrived before that build is not recorded.

Severity by source

Bitnami9.3CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:N

Trivy's own label is CRITICAL. Rated critical by Bitnami.

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.

Affected packages and fixed versions

Source	Package	Fixed in
bitnami::Bitnami Vulnerability Database	discourse	2026.1.6, 2026.5.2, 2026.6.1

References

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