CVE-2017-18195 in concrete5
Summary
by MITRE
An issue was discovered in tools/conversations/view_ajax.php in Concrete5 before 8.3.0. An unauthenticated user can enumerate comments from all blog posts by POSTing requests to /index.php/tools/required/conversations/view_ajax with incremental 'cnvID' integers.
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Analysis
by VulDB Data Team • 08/24/2025
This vulnerability exists in Concrete5 content management system versions prior to 8.3.0, specifically within the tools/conversations/view_ajax.php component that handles conversation and comment display functionality. The flaw represents a classic information disclosure vulnerability where an attacker can systematically enumerate comments from all blog posts without requiring authentication or authorization. The vulnerability stems from inadequate input validation and access control mechanisms within the conversation viewing endpoint, allowing malicious actors to exploit the system's lack of proper permission checks.
The technical implementation of this vulnerability leverages the incremental cnvID parameter that is passed through POST requests to the view_ajax endpoint. When an attacker submits requests with sequentially increasing cnvID values, the system responds with comment data from each corresponding conversation thread without verifying whether the requester has legitimate access to view those comments. This exposes the underlying architecture's failure to implement proper access controls for conversation data, which should typically be restricted to authorized users or those with appropriate permissions. The vulnerability operates at the application layer and demonstrates a fundamental flaw in the authorization model where conversation threads are treated as publicly accessible resources regardless of their content or intended audience.
The operational impact of this vulnerability is significant as it enables comprehensive comment enumeration across all blog posts within a Concrete5 installation. Attackers can systematically discover and extract comment data from every conversation thread, potentially exposing sensitive information, user interactions, or internal discussions that were not intended for public viewing. This information disclosure could reveal user behavior patterns, internal discussions, or potentially sensitive data shared in comments that might include personal information, business discussions, or other confidential content. The vulnerability effectively bypasses the platform's intended access controls and could facilitate further attacks such as social engineering or reconnaissance activities.
Security professionals should implement immediate mitigations including upgrading to Concrete5 version 8.3.0 or later where this vulnerability has been addressed through proper access control enforcement. The fix typically involves implementing robust input validation and authentication checks within the view_ajax endpoint to ensure that only authorized users can access conversation data. Organizations should also consider implementing rate limiting and monitoring for unusual patterns of cnvID parameter usage to detect potential exploitation attempts. This vulnerability aligns with CWE-284 Access Control Issues and could be categorized under ATT&CK technique T1213 Data from Information Repositories, representing a critical weakness in access control mechanisms that allows unauthorized data enumeration.