Concrete CMS vulnerable to Reflected Cross-Site Scripting (XSS) in Conversation Messages Dashboard Page

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.

Basic information

Type
reviewed
Severity
medium
Advisory on GitHub
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Repository advisory
Source code
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Published (advisory)
2025-08-06 00:30:25 UTC
Updated
2025-08-06 17:24:48 UTC
GitHub reviewed
2025-08-06 17:24:47 UTC
NVD published
2025-08-05

EPSS Score

Score Percentile
0.08% 23.72%

CVSS Scores

Base score Version Severity Vector
4.8 4.0
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 Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network.
Attack complexity (AC:L)
Exploitation conditions are straightforward and stable.
Attack requirements (AT:N)
No additional preconditions are required beyond normal reachability.
Privileges required (PR:H)
High privileges are required.
User interaction (UI:P)
A user has to participate (for example click/open/approve).
Vulnerable system confidentiality impact (VC:L)
Limited confidentiality impact on the vulnerable system.
Vulnerable system integrity impact (VI:L)
Limited integrity impact on the vulnerable system.
Vulnerable system availability impact (VA:N)
No availability impact on the vulnerable system.
Subsequent system confidentiality impact (SC:N)
No confidentiality impact on subsequent systems.
Subsequent system integrity impact (SI:N)
No integrity impact on subsequent systems.
Subsequent system availability impact (SA:N)
No availability impact on subsequent systems.

Identifiers

CWEs

CWE id Name
CWE-20 Improper Input Validation
CWE-79 Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')

Affected packages (2)

Vulnerable version ranges and first patched releases as published by GitHub.

Ecosystem Package Vulnerable range First patched Vulnerable functions
composer concrete5/concrete5 < 8.5.21 8.5.21
composer concrete5/concrete5 >= 9.0.0RC1, < 9.4.3 9.4.3

References

cvelogic Threat Intelligence