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

Is it exploited?

Yes. CISA added it to the Known Exploited Vulnerabilities catalog on 3 Nov 2021, 674 days after the CVE record was published.

How likely is exploitation in the next 30 days?

98.6%

EPSS score, percentile 99.9 of all scored records

How severe?

7.5 High

CVSS v3.1 base score, from CISA's enrichment of the record

What should I do?

Required action (CISA), due 3 May 2022: Apply updates per vendor instructions.

The CVE record links no vendor advisory, patch or mitigation.

Which versions are affected?

Affected: Apache Solr 5.0.0 to Apache Solr 8.3.1

Versions by product

Source: CISA Known Exploited Vulnerabilities (KEV) catalog, 2026.10.28, as of 28 Oct 2026; FIRST Exploit Prediction Scoring System (EPSS), v2026.06.15, as of 28 Oct 2026; CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of 28 Oct 2026. About the data.

What to do

CISA due date for this action: 3 May 2022.

Advisories and patches

The CVE record links no vendor advisory, patch or mitigation.

Linked from CISA's catalog entry

• https://nvd.nist.gov/vuln/detail/CVE-2019-17558

Affected products and versions

As listed in the CVE record.

Source: CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of 28 Oct 2026. About the data.

About this vulnerability

The Apache Solr VelocityResponseWriter plug-in contains an unspecified vulnerability which can allow for remote code execution.

Summary: CISA's KEV catalog, as of 28 Oct 2026.

• CISA added CVE-2019-17558 to its Known Exploited Vulnerabilities (KEV) catalog on 3 Nov 2021.
• CISA's ransomware flag for this entry is "Unknown": no evidence of ransomware use in the catalog, which is not proof of none.
• The due date CISA sets for the required action is 3 May 2022.
• The CVE record was published on 30 Dec 2019, 674 days before it was added to KEV.
• The CVE record carries a CVSS v3.1 base score of 7.5 (High), taken from CISA's enrichment of the record.
• FIRST's EPSS model puts the probability of exploitation in the next 30 days at 98.6% (percentile 99.9), as of 28 Oct 2026.
• CISA's SSVC assessment in the CVE record: exploitation active, automatable no, technical impact total.

Source: CISA Known Exploited Vulnerabilities (KEV) catalog, 2026.10.28, as of 28 Oct 2026; CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of 28 Oct 2026; FIRST Exploit Prediction Scoring System (EPSS), v2026.06.15, as of 28 Oct 2026. About the data.

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).

Source: CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of 28 Oct 2026. About the data.

Weakness

• CWE-74: Improper Neutralization of Special Elements in Output Used by a Downstream Component ('Injection')

CWE and CAPEC are maintained by MITRE; the entries are those named in the CVE record and the KEV entry.

Timeline

References

• [lucene-issues] 20200107 [jira] [Commented] (SOLR-13971) CVE-2019-17558: Velocity custom template RCE vulnerability
• [lucene-issues] 20200108 [jira] [Commented] (SOLR-13971) CVE-2019-17558: Velocity custom template RCE vulnerability
• [lucene-issues] 20200108 [jira] [Updated] (SOLR-14025) CVE-2019-17558: Velocity response writer RCE vulnerability persists after 8.3.1
• [lucene-issues] 20200108 [GitHub] [lucene-solr] Sachpat opened a new pull request #1156: SOLR-13971
• [lucene-issues] 20200108 [GitHub] [lucene-solr] Sachpat commented on a change in pull request #1156: SOLR-13971: CVE-2019-17558: Velocity custom template RCE v…
• [lucene-issues] 20200108 [GitHub] [lucene-solr] artem-smotrakov commented on a change in pull request #1156: SOLR-13971: CVE-2019-17558: Velocity custom templa…
• [lucene-issues] 20200108 [GitHub] [lucene-solr] Sachpat commented on issue #1156: SOLR-13971: CVE-2019-17558: Velocity custom template RCE vulnerability
• [lucene-issues] 20200113 [GitHub] [lucene-solr] Sachpat closed pull request #1156: SOLR-13971: CVE-2019-17558: Velocity custom template RCE vulnerability
• [lucene-issues] 20200113 [jira] [Commented] (SOLR-14025) CVE-2019-17558: Velocity response writer RCE vulnerability persists after 8.3.1
• [lucene-issues] 20200113 [GitHub] [lucene-solr] chatman commented on issue #1156: SOLR-13971: CVE-2019-17558: Velocity custom template RCE vulnerability
• [lucene-issues] 20200113 [GitHub] [lucene-solr] Sachpat commented on issue #1156: SOLR-13971: CVE-2019-17558: Velocity custom template RCE vulnerability
• [lucene-dev] 20200213 Re: 7.7.3 bugfix release

17 more in the CVE record.

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