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

Severity: high (CVSS 7.5 v3.1)
Exploited in the wild: yes — in CISA KEV since 2021-11-03
EPSS: 98.6% probability of exploitation in the next 30 days
Public exploit or detection template: yes
Published: 2019-12-30 · updated 2026-06-17
Weakness: CWE-74

Description

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 Software Foundation Apache Solr: from 5.0.0 before 7.7.3; from 8.0.0 before 8.4.0 — fixed in 7.7.3, 8.4.0
Oracle Corporation Primavera Unifier: from 17.7 through 17.12; 16.1, 16.2, 18.8, 19.12

How to fix

Upgrade to a fixed version: Apache Software Foundation Apache Solr 7.7.3, 8.4.0. Check the vendor advisory for mitigations.

References

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