CVE-2026-55674

LOWCVSS 9.3 · CRITICAL

Signal is active with 1 mentions in latest observed window

Immediate actions

Track advisory updates for patch or workaround availability

Recommended action window: Monitor and triage in normal cycle

NVD 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.

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0.0/ 10 priority

Sources & remediation

Other references

https://github.com/discourse/discourse/security/advisories/GHSA-qx4v-rg4v-pm2g

Weakness type (CWE)

CWE-79

Priority

LOW

Exploitation

NONE

PoC

NONE

Patch

NONE

Momentum

NONE

Threat summary

1 mentions across 1 observed day

What's happening

1 total mentions across 1 day

Deep dive

Activity timeline1 mentions / 1d

Full discourse1 post

Assetnote@assetnote15h
Our research team discovered two vulnerabilities in Discourse: a pre-authentication cache poisoning to sitewide XSS (CVE-2026-55674), and an arbitrary file read (RCE) chaining a JPEG race condition with ImageMagick and Ghostscript (CVE-2026-55420). You can read more here: https://t.co/twDxtwCnoQ
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