CVE-2022-43689 in Concrete
Summary
by MITRE • 11/15/2022
Concrete CMS (formerly concrete5) below 8.5.10 and between 9.0.0 and 9.1.2 is vulnerable to XXE based DNS requests leading to IP disclosure.
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Analysis
by VulDB Data Team • 04/30/2025
Concrete CMS versions prior to 8.5.10 and between 9.0.0 and 9.1.2 contain a critical vulnerability that allows attackers to perform XML External Entity processing attacks resulting in unauthorized DNS resolution requests and subsequent IP address disclosure. This vulnerability stems from insufficient input validation and sanitization within the application's XML parsing functionality, which fails to properly restrict external entity references during document processing. The flaw enables remote attackers to craft malicious XML payloads that trigger the application to resolve external DNS records, effectively exposing internal network IP addresses and potentially revealing sensitive infrastructure information.
The technical implementation of this vulnerability occurs when the CMS processes XML data containing external entity declarations that reference external resources. When the application parses such malformed XML input without proper validation, it automatically resolves the external entity references, creating DNS requests to external servers that can be monitored by attackers. This behavior violates security principle of least privilege and demonstrates a classic XML external entity injection vulnerability pattern. The vulnerability aligns with CWE-611, which specifically addresses Improper Restriction of XML External Entity Reference, and represents a significant information disclosure risk that can be leveraged for further reconnaissance activities. Attackers can exploit this weakness to map internal network topology, identify active services, and potentially discover other vulnerable systems within the same network segment.
The operational impact of this vulnerability extends beyond simple information disclosure, as it provides attackers with crucial intelligence for subsequent attack phases. Network reconnaissance capabilities gained through DNS resolution requests can be combined with other vulnerabilities to create more sophisticated attack vectors. The vulnerability affects both the 8.x and 9.x release branches, indicating a widespread issue that impacts a significant portion of Concrete CMS installations. Organizations running affected versions face potential exposure to advanced persistent threats that can use the disclosed IP addresses to plan targeted attacks against internal services, potentially leading to full system compromise. The vulnerability also violates fundamental security practices outlined in the OWASP Top Ten, specifically addressing injection flaws and information leakage concerns.
Mitigation strategies for this vulnerability require immediate patching of affected Concrete CMS installations to versions 8.5.10 or 9.1.3 and later. Organizations should implement proper XML parsing configurations that disable external entity resolution and parameter entity expansion. Network-level protections including DNS filtering and traffic monitoring can help detect anomalous DNS requests originating from the CMS servers. Security teams should conduct comprehensive vulnerability assessments to identify all instances of the affected software across their infrastructure. The remediation process should include disabling unnecessary XML processing capabilities and implementing strict input validation for all XML data processing within the application. Additionally, organizations should consider implementing network segmentation and firewall rules to limit outbound DNS requests from CMS servers, reducing the attack surface and preventing unauthorized information disclosure. This vulnerability demonstrates the critical importance of maintaining up-to-date software components and implementing defense-in-depth strategies to protect against information disclosure threats.