CVE-2019-17558: Apache Solr VelocityResponseWriter Plug-In Remote Code Execution Vulnerability

High severity, CVSS 7.5. Actively exploited: in CISA KEV since 2021-11-03. EPSS: 98.6% chance of exploitation in the next 30 days.

Apache Solr 5.0.0 to Apache Solr 8.3.1 are vulnerable to a Remote Code Execution through the VelocityResponseWriter. A Velocity template can be provided through Velocity templates in a configset `velocity/` directory or as a parameter. A user defined configset could contain renderable, potentially malicious, templates. Parameter provided templates are disabled by default, but can be enabled by setting `params.resource.loader.enabled` by defining a response writer with that setting set to `true`. Defining a response writer requires configuration API access. Solr 8.4 removed the params resource loader entirely, and only enables the configset-provided template rendering when the configset is `trusted` (has been uploaded by an authenticated user).

Affected products

• Apache Solr: from 5.0.0, before 7.7.3 (fixed in 7.7.3); from 8.0.0, before 8.4.0 (fixed in 8.4.0)
• Oracle Primavera Unifier: from 17.7, up to and including 17.12; version 16.1 only; version 16.2 only; version 18.8 only; version 19.12 only

Published 2019-12-30. Last modified 2026-06-17.