How severe is GHSA-45fj-fvmm-xcc5?

No CVSS score has been assigned to GHSA-45fj-fvmm-xcc5 yet. Review the advisory details and affected package list to assess your exposure.

Which packages are affected by GHSA-45fj-fvmm-xcc5?

GHSA-45fj-fvmm-xcc5 affects the following packages: concrete5/concrete5 (Packagist). Ecosystems affected: Packagist.

How do I fix GHSA-45fj-fvmm-xcc5?

Update concrete5/concrete5 to 9.4.8 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-45fj-fvmm-xcc5 is resolved across your whole dependency graph.

How do I detect GHSA-45fj-fvmm-xcc5 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-45fj-fvmm-xcc5 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-45fj-fvmm-xcc5 actively exploited in the wild?

No public exploit code has been indexed for GHSA-45fj-fvmm-xcc5 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-45fj-fvmm-xcc5?

GHSA-45fj-fvmm-xcc5 has an EPSS (Exploit Prediction Scoring System) score of 0.2%, placing it in the 16th 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-45fj-fvmm-xcc5?

GHSA-45fj-fvmm-xcc5 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-45fj-fvmm-xcc5 published, and has it been updated?

GHSA-45fj-fvmm-xcc5 was published on March 4, 2026 and was last updated on March 4, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

🐘 Packagist

Not in CISA KEV

Concrete CMS has a stored Cross-site Scripting (XSS) vulnerabilityGHSA-45fj-fvmm-xcc5

Fix: concretecms/concretecms#12826

GHSA-45fj-fvmm-xcc5 is a Cross-site Scripting (XSS) vulnerability in concrete5/concrete5. A fix is available for concrete5/concrete5 — see the affected versions and patch details below.

Also known asCVE-2026-3240

Published

Mar 4, 2026

Updated

Mar 4, 2026

Affected

1 pkg

Patched

1 / 1

Exploits

None indexed

Exploitation data as of Nov 4, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

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-45fj-fvmm-xcc5.

EPSS Exploitation Probability

via FIRST.org ↗

0.2%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs16th percentile — riskier than 16% 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

In Concrete CMS below version 9.4.8, a user with permission to edit a page with element Legacy form can perform a stored XSS attack towards high-privilege accounts via the Question field. The Concrete CMS security team gave this vulnerability a CVSS v.4.0 score of 4.8 with vector CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:P/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N Thanks minhnn42, namdi and quanlna2 from VCSLab-Viettel Cyber Security for reporting.

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
🐘Packagist	`concrete5/concrete5`	all versions	9.4.8`composer require concrete5/concrete5:^9.4.8`

Affected Products

1 product · 1 configurations

Application

concrete cmsconcretecms

< 9.4.8

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 9.4.8 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-45fj-fvmm-xcc5 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

In Concrete CMS below version 9.4.8, a user with permission to edit a page with element Legacy form can perform a stored XSS attack towards high-privilege accounts via the Question field. The Concrete CMS security team thanks minhnn42, namdi and quanlna2 from VCSLab-Viettel Cyber Security for reporting.

O3 Security · Impact-Aware SCA

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