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MEDIUM severity

GHSA-437p-jfm4-2387 — concrete5/concrete5

MEDIUM

GHSA-437p-jfm4-2387 is a medium-severity (CVSS 5.4) Cross-site Scripting (XSS) vulnerability in concrete5/concrete5. 1 public exploit reference exists, so weaponization risk is real. No vendor fix is recorded yet; mitigation options are listed below.

ConcreteCMS Cross-site Scripting vulnerability

Also known asCVE-2023-44766
Published
Oct 6, 2023
Updated
Sep 10, 2026
Affected
1 pkg
Patched
See advisory
Exploits
1 known
Exploitation data as of Sep 26, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗
0.6%probability of exploitation in next 30 days
Lower Risk0.00%
Lower risk than most CVEs44th percentile — riskier than 44% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

GHSA-437p-jfm4-2387 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.

Where this sits among everything scored

Of 379,842 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Counts from FIRST.org, log-scaled.

Real-World Exposure

1 pkg affected
🐘concrete5/concrete5

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects Packagist packages — download data is not available via public APIs for these ecosystems.

Description

A Cross Site Scripting (XSS) vulnerability in Concrete CMS v.9.2.1 allows an attacker to execute arbitrary code via a crafted script to the SEO - Extra from Page Settings. NOTE: the vendor disputes this because this SEO-related header change can only be made by an admin, and allowing an admin to place JavaScript there is an intentional customization feature.

Affected Packages

1 total
EcosystemPackageVulnerable rangeFix
🐘Packagistconcrete5/concrete5all versionsNo fix

Affected Products

1 product · 1 configurations
Application
concrete cmsconcretecms
1 version
9.2.1
Exploits & PoCs
1

Research use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.

A Cross Site Scripting (XSS) vulnerability in Concrete CMS v.9.2.1 allow…

github.comNVDOct 2023

Detection & mitigation playbook

Open-source dependency

  1. Detect

    Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for concrete5/concrete5, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

  2. Remediation status

    No patched version of concrete5/concrete5 has shipped for GHSA-437p-jfm4-2387 yet. Where your build allows, override or pin the dependency away from the vulnerable range, and apply any maintainer-recommended mitigation.

  3. Mitigate without a patch

    Escape or sanitise the affected output on the server side rather than relying on client-side filtering, and add a Content-Security-Policy that blocks inline script execution so injected markup cannot run even if it reaches the page.

Frequently Asked Questions

A Cross Site Scripting (XSS) vulnerability in Concrete CMS v.9.2.1 allows an attacker to execute arbitrary code via a crafted script to the SEO - Extra from Page Settings.
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