CVE-2025-8571: concrete cms Input Validation Flaw

Description

Concrete CMS 9 to 9.4.2 and versions below 8.5.21 are vulnerable to Reflected Cross-Site Scripting (XSS) in the Conversation Messages Dashboard Page. Unsanitized input could cause theft of session cookies or tokens, defacement of web content, redirection to malicious sites, and (if victim is an admin), the execution of unauthorized actions. 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:L/VI:L/VA:N/SC:N/SI:N/SA:N. Thanks Fortbridge https://fortbridge.co.uk/ for performing a penetration test and vulnerability assessment on Concrete CMS and reporting this issue.

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CVSS v3.1 Score

4.8

MEDIUM

CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:C/C:L/I:L/A:N

Weakness Type (CWE)

CWE-20 Improper Input Validation

CWE-79 Cross-site Scripting (XSS)

Affected Products

Vendor	Product	Versions
concretecms	concrete_cms	< 8.5.21
concretecms	concrete_cms	9.0 — 9.4.3

References

Other References

https://documentation.concretecms.org/9-x/developers/introduction/version-history/943-release-notes https://documentation.concretecms.org/developers/introduction/version-history/8521-release-notes https://www.concretecms.org/download

Frequently Asked Questions

What is CVE-2025-8571? +

Concrete CMS 9 to 9.4.2 and versions below 8.5.21 are vulnerable to Reflected Cross-Site Scripting (XSS) in the Conversation Messages Dashboard Page. Unsanitized input could cause theft of session cookies or tokens, defacement of web content, redirection to malicious sites, and (if victim is an admin), the execution of unauthorized actions. 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:L/VI:L/VA:N/SC:N/SI:N/SA:N. Thanks Fortbridge https://fortbridge.co.uk/ for performing a penetration test and vulnerability assessment on Concrete CMS and reporting this issue. It has a CVSS v3.1 base score of 4.8 (MEDIUM).

How severe is CVE-2025-8571? +

CVE-2025-8571 has a CVSS v3.1 score of 4.8 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance.

What products are affected by CVE-2025-8571? +

CVE-2025-8571 affects products from concretecms, specifically: concrete_cms. Check the affected products table above for specific version ranges.

How do I check if I'm vulnerable to CVE-2025-8571? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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