CVE-2019-0193: Apache Solr DataImportHandler Code Injection Vulnerability

CVE-2019-0193 is a code injection vulnerability in the optional DataImportHandler module of Apache Solr. When that module is present and reachable, an attacker may be able to inject and run unauthorized code in the Solr process. That matters because Solr often sits close to search indexes and application data; successful abuse can lead to full compromise of the host or lateral movement into connected systems.

Public detail is limited to the fact that the flaw is code injection (CWE-94) in this optional module. Exact affected versions, attack prerequisites, and scoring must be confirmed against the vendor advisory. CISA lists the required action as applying updates per vendor instructions; ransomware use is not documented for this CVE.

How it works

CWE-94 covers improper control of code generation or evaluation—situations where untrusted input is treated as executable code. In this case the optional DataImportHandler component is the affected surface. DataImportHandler is designed to pull data from external sources into Solr; if it accepts attacker-controlled configuration or parameters without sufficient validation, that input can be interpreted as code rather than data.

An attacker who can reach the vulnerable handler (for example via an exposed Solr admin or request handler interface) would attempt to supply crafted input that the module then executes in the context of the Solr process. The precise injection point and required privileges are not detailed in the provided facts; defenders should treat any network-accessible DataImportHandler endpoint as potentially abusable until the vendor advisory is reviewed and the module is confirmed patched or disabled. No exploit mechanics or proof-of-concept details are supplied here and should not be assumed.

Am I affected? How to find it in your systems

Apache Solr is commonly deployed as a standalone search server, embedded in applications, or run inside containers and orchestration platforms. It frequently appears in content-management, e-commerce, analytics, and log-search stacks. Inventory every instance:

• Search configuration management, CMDB, and container image registries for packages or images named solr or apache-solr.
• Scan internal networks for hosts listening on typical Solr ports and examine process lists for Java processes running Solr.
• Inspect Solr home directories and solrconfig.xml (or equivalent) for the DataImportHandler (often referenced as DIH) request handler or related libraries; the module is optional, so its presence is the key indicator.
• Check version strings reported by the Solr admin UI, INFO logs at startup, or package managers, then compare them to the fixed versions listed in the vendor advisory.

Telemetry signs of exploitation are not specified in the facts. In general for this class, look for unexpected requests to DataImportHandler endpoints, sudden configuration changes, unusual outbound connections from the Solr process, or new child processes spawned by the Java runtime. Correlate with authentication logs if the admin interface is exposed. Confirm any concrete indicators against the vendor advisory and your own baseline.

How to remediate

Patch first. Apply the updates published by the Apache Solr project exactly as described in the vendor advisory for CVE-2019-0193. CISA’s required action is to apply updates per vendor instructions; do not rely on version guesses—verify the fixed release on the official advisory.

After patching:

• Restart Solr instances in a controlled manner and confirm the DataImportHandler (if still required) loads the updated code.
• If the module is not needed, remove or disable it entirely from solrconfig.xml and delete associated JARs to shrink the attack surface.
• Restrict network access to Solr admin and request-handler interfaces to trusted management networks only; enforce authentication and least-privilege accounts.
• Run Solr under a dedicated low-privilege OS user and apply standard Java hardening (security manager where practical, up-to-date JRE, minimal filesystem permissions).
• Re-scan and re-inventory to ensure no unpatched replicas, snapshots, or container images remain.

If you can't patch immediately

Until the vendor update can be applied, reduce exposure with compensating controls:

• Disable or unload the DataImportHandler module so the vulnerable code path is not reachable.
• Segment Solr hosts behind firewalls or security groups that allow only application-tier and administrative jump hosts; block direct internet or broad internal access.
• Place a reverse proxy or WAF in front of Solr and deny or tightly restrict requests that target DataImportHandler paths or parameters; treat this as virtual patching only, not a substitute for the real fix.
• Increase monitoring: alert on any access to DIH-related endpoints, configuration reloads, or anomalous process behavior; forward Solr and system logs to a central SIEM.
• Ensure backups of indexes and configs are current and tested so recovery is possible if compromise occurs.

These steps lower risk but do not eliminate it; schedule the official patch as soon as practicable.

If your data may have been exposed

Actively exploited vulnerabilities can lead to unauthorized access, data theft, or further compromise of connected systems. If you have reason to believe an unpatched Solr instance was reachable and the DataImportHandler was enabled, treat the host as potentially compromised: isolate it, preserve logs and memory images for investigation, rotate credentials that the Solr process could access, and review downstream systems for lateral movement. Ransomware use is not documented for this CVE, but standard incident-response practice still applies. As a quick additional check, you can run a free exposure scan of your email addresses against known breach data sets to see whether associated credentials have appeared in prior public breaches.