This vulnerability in Apache Solr 6.0.0 to 6.6.3, 7.0.0 to 7.3.0 relates to an XML external entity expansion (XXE) in Solr config files (solrconfig.xml, schema.xml, managed-schema). In addition, Xinclude functionality provided in these config files is also affected in a similar way. The vulnerability can be used as XXE using file/ftp/http protocols in order to read arbitrary local files from the Solr server or the internal network. Users are advised to upgrade to either Solr 6.6.4 or Solr 7.3.1 releases both of which address the vulnerability. Once upgrade is complete, no other steps are required. Those releases only allow external entities and Xincludes that refer to local files / zookeeper resources below the Solr instance directory (using Solr's ResourceLoader); usage of absolute URLs is denied. Keep in mind, that external entities and XInclude are explicitly supported to better structure config files in large installations. Before Solr 6 this was no problem, as config files were not accessible through the APIs.
| Software | From | Fixed in |
|---|---|---|
| apache / solr | 6.0.0 | 6.6.3.x |
| apache / solr | 7.0.0 | 7.3.0.x |
org.apache.solr / solr-core
|
6.6.0 | 6.6.4 |
org.apache.solr / solr-core
|
7.0.0 | 7.3.1 |
A security vulnerability is a weakness in software, hardware, or configuration that can be exploited to compromise confidentiality, integrity, or availability. Many vulnerabilities are tracked as CVEs (Common Vulnerabilities and Exposures), which provide a standardized identifier so teams can coordinate patching, mitigation, and risk assessment across tools and vendors.
CVSS (Common Vulnerability Scoring System) estimates technical severity, but it doesn't automatically equal business risk. Prioritize using context like internet exposure, affected asset criticality, known exploitation (proof-of-concept or in-the-wild), and whether compensating controls exist. A "Medium" CVSS on an exposed, production system can be more urgent than a "Critical" on an isolated, non-production host.
A vulnerability is the underlying weakness. An exploit is the method or code used to take advantage of it. A zero-day is a vulnerability that is unknown to the vendor or has no publicly available fix when attackers begin using it. In practice, risk increases sharply when exploitation becomes reliable or widespread.
Recurring findings usually come from incomplete Asset Discovery, inconsistent patch management, inherited images, and configuration drift. In modern environments, you also need to watch the software supply chain: dependencies, containers, build pipelines, and third-party services can reintroduce the same weakness even after you patch a single host. Unknown or unmanaged assets (often called Shadow IT) are a common reason the same issues resurface.
Use a simple, repeatable triage model: focus first on externally exposed assets, high-value systems (identity, VPN, email, production), vulnerabilities with known exploits, and issues that enable remote code execution or privilege escalation. Then enforce patch SLAs and track progress using consistent metrics so remediation is steady, not reactive.
SynScan combines attack surface monitoring and continuous security auditing to keep your inventory current, flag high-impact vulnerabilities early, and help you turn raw findings into a practical remediation plan.