XSS in Concrete Cms

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.

Vulnerability class: Drupalgeddon 2 (CVE-2018-7600)

Published · last modified .

CVSS v3 metric

CVSS v3 base score 4.8 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:C/C:L/I:L/A:N.

EPSS exploit prediction

EPSS: 0.003 (22.4th percentile), scored .

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 22nd percentile — 22.4% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS trend (30 days)EPSS over the last 30 days for CVE-2025-8571: held from 0.003 to 0.003.

EPSS over last 30 days · oldest: 0.003 · newest: 0.003 · change: 0.000

Affected products

Weakness classification (CWE)

Public proof-of-concept exploits

References

Frequently asked questions

What is CVE-2025-8571?
CVE-2025-8571 is a medium-severity vulnerability in Concrete Cms, classified under Improper Input Validation. CVSS score: 4.8/10. Published 2025-08-05.
How severe is CVE-2025-8571?
Medium severity. CVSS v3 base score is 4.8 out of 10.
Is CVE-2025-8571 known to be exploited?
3 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.