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

Vulnerability summary

CVE-2019-17558 is a high (CVSS 7.5) Injection vulnerability in Apache Solr. It is known to be exploited: CISA lists it, first on 03-11-2021. EPSS estimates a 98.57% chance of exploitation in the next 30 days, higher than 99.9% of scored vulnerabilities. 7 public exploits are recorded.

Timeline

1. 30-12-2019
   PublishedVulnerability first disclosed.
2. 03-11-2021
   Added to CISA KEVApache Solr VelocityResponseWriter Plug-In Remote Code Execution Vulnerability
3. 03-05-2022
   CISA remediation dueApply updates per vendor instructions.
4. 21-10-2025
   Last modifiedVulnerability information updated.

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).

• CWE-74Improper Neutralization of Special Elements in Output Used by a Downstream Component ('Injection')The product constructs all or part of a command, data structure, or record using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify how it is parsed or interpreted when it is sent to a downstream component.