Secuno
ENNL
Book demo

CVE-2026-55674

Discourse cross-site scripting (XSS)

9.3 CRITICALEPSS 0.59%
  1. Published17 Aug 2026

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.

CVSS 3.1 breakdown

Attack vectorNetwork
Attack complexityLow
Privileges requiredNone
User interactionRequired
ScopeChanged
ConfidentialityHigh
IntegrityHigh
AvailabilityNone
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:N

Remediation

No fixed version is recorded in the NVD data. Check the vendor advisory for the latest guidance.

References

Related CVEs

Recent high-severity vulnerabilities sharing a weakness type.

CVE-2026-928838.7
GitLab has remediated an issue in GitLab CE/EE affecting all versions from 19.1 before…
CVE-2026-938868.3
IBM i 7.3, 7.4, 7.5, and 7.6 could allow a remote authenticated attacker to execute…
CVE-2026-1096338.1
Frappe ERPNext before 15.119.1 and 16.x before 16.32.0 contains a stored cross-site…
CVE-2025-714328.1
Frappe ERPNext before 14.92.1 and 15.x before 15.83.0 contains a reflected cross-site…
CVE-2026-1095588.7
EdgeEver 1.6.0 through 1.112.0 contains a stored cross-site scripting vulnerability in…
CVE-2026-1095578.7
EdgeEver through 1.112.0 contains a stored cross-site scripting vulnerability in…

Frequently asked

Is CVE-2026-55674 being actively exploited?

CVE-2026-55674 is not in the CISA KEV catalog. Its EPSS exploit probability is 0.59%.

How severe is CVE-2026-55674?

CVE-2026-55674 has a CVSS 3.1 base score of 9.3, rated critical. EPSS estimates a 0.59% probability of exploitation.

How do I fix CVE-2026-55674?

Apply the vendor's patch or advisory guidance, then verify no affected versions remain across your devices.

How Secuno handles this

Secuno correlates vulnerabilities like CVE-2026-55674 against the real software inventory on every managed device, every day. Rather than a static severity, each match is scored in context: exploit availability, EPSS, the asset's exposure, and business criticality decide where it lands in the queue. If an affected version is present anywhere across your portfolio, it surfaces automatically with a prioritised remediation path.

See how prioritisation worksBook a demo

Get Patch this first every Monday

Five vulnerabilities that matter this week, ranked on real exploitation. Plain language, one email, no spam.

You can unsubscribe with one click from every issue. We handle your details as described in our privacy policy.

Data from the NVD, CISA KEV catalog and FIRST EPSS. CVSS 3.1 base score shown where available.