How severe is GHSA-q9fm-mpg8-8jqm?

No CVSS score has been assigned to GHSA-q9fm-mpg8-8jqm yet. Review the advisory details and affected package list to assess your exposure.

Which packages are affected by GHSA-q9fm-mpg8-8jqm?

GHSA-q9fm-mpg8-8jqm affects the following packages: concrete5/concrete5 (Packagist). Ecosystems affected: Packagist.

How do I fix GHSA-q9fm-mpg8-8jqm?

Update concrete5/concrete5 to 9.5.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-q9fm-mpg8-8jqm is resolved across your whole dependency graph.

How do I detect GHSA-q9fm-mpg8-8jqm in my Packagist dependencies?

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.

How do I mitigate GHSA-q9fm-mpg8-8jqm if there is no patch (or I can't update yet)?

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.

Is GHSA-q9fm-mpg8-8jqm actively exploited in the wild?

No public exploit code has been indexed for GHSA-q9fm-mpg8-8jqm yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What is the EPSS score for GHSA-q9fm-mpg8-8jqm?

GHSA-q9fm-mpg8-8jqm has an EPSS (Exploit Prediction Scoring System) score of 0.3%, placing it in the 15th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is GHSA-q9fm-mpg8-8jqm?

GHSA-q9fm-mpg8-8jqm is classified as Cross-site Scripting (XSS) (CWE-79). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation. This is a high-impact weakness class that often enables remote code execution or data exposure.

When was GHSA-q9fm-mpg8-8jqm published, and has it been updated?

GHSA-q9fm-mpg8-8jqm was published on May 26, 2026 and was last updated on September 10, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

Concrete CMS is vulnerable to Stored XSS via page name…

Exploitation Status

No confirmed exploitation observed yet

CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.

Exploitation and automatability from CISA’s SSVC triage for GHSA-q9fm-mpg8-8jqm.

EPSS Exploitation Probability

via FIRST.org ↗

0.3%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs15th percentile — riskier than 15% of all scored CVEsHighest risk

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

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

Concrete CMS version 9.0 to 9.5.0 is vulnerable to Stored XSS via page name in the Atomik theme. A rogue editor can inject arbitrary JavaScript that executes in the context of any authenticated user visiting the affected account pages. This can lead to session hijacking, credential theft, malicious actions performed on behalf of users, and potential privilege escalation. The Concrete CMS security team gave this vulnerability a CVSS v.4.0 score of 2.1 with vector CVSS:4.0/AV:N/AC:L/AT:P/PR:H/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N. Thanks Yonatan Drori (Tenzai) for reporting.

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
🐘Packagist	`concrete5/concrete5`	≥ 9.0.0RC.1&&< 9.5.1	9.5.1`composer require concrete5/concrete5:^9.5.1`

Affected Products

1 product · 1 configurations

Application

concrete cmsconcretecms

≥ 9.0 && < 9.5.1

range

Detection & mitigation playbook

Open-source dependency

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.
Fix
Update concrete5/concrete5 to 9.5.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-q9fm-mpg8-8jqm is resolved across your whole dependency graph.
Workarounds
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

Concrete CMS version 9.0 to 9.5.0 is vulnerable to Stored XSS via page name in the Atomik theme. A rogue editor can inject arbitrary JavaScript that executes in the context of any authenticated user visiting the affected account pages. This can lead to session hijacking, credential theft, malicious actions performed on behalf of users, and potential privilege escalation. Thanks Yonatan Drori (Tenzai) for reporting.

O3 Security · Impact-Aware SCA

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Concrete CMS is vulnerable to Stored XSS via page name in the Atomik themeGHSA-q9fm-mpg8-8jqm