Apache Solr VelocityResponseWriter Plug-In Remote Code Execution
CVE-2019-17558 is a high-severity improper neutralization of special elements in output used by a downstream component vulnerability in Apache Solr, with a CVSS 3.1 base score of 7.5 out of 10. It can be exploited remotely over the network by an attacker with a low-privileged account, without any action from a user. Affected Apache Solr versions: Apache Solr 5.0.0 to Apache Solr 8.3.1. The record does not name a fixed version, so check the vendor advisory. CISA added it to the Known Exploited Vulnerabilities catalogue on November 3, 2021, which means attacks have been observed in the wild.
Attackers are already exploiting this vulnerability, according to CISA.
What to do
- Update Solr to 7.7.3 or 8.4.0, whichever matches your release line, or a later version.
- CISA's required action: Apply updates per vendor instructions.
- Read the advisory on issues.apache.org for workarounds and exact fixed builds.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Apache Solr | Apache Solr | Apache Solr 5.0.0 to Apache Solr 8.3.1 | Not stated |
| Apache | Solr | 5.0.0 up to, but not including, 7.7.3; 8.0.0 up to, but not including, 8.4.0 | 7.7.3, 8.4.0 |
| Oracle | Primavera Unifier | 17.7 through 17.12; 16.1; 16.2; 18.8; 19.12 | Not stated |
Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.
How the severity score breaks down
- Attack vector
- NetworkCan be exploited remotely over a network, including the internet.
- Attack complexity
- HighSuccess depends on conditions outside the attacker's control.
- Privileges required
- LowA basic user account is enough.
- User interaction
- NoneNo action by a victim is required.
- Scope
- UnchangedImpact stays within the vulnerable component.
- Confidentiality
- HighAll data handled by the component can be read.
- Integrity
- HighData or code can be modified at will.
- Availability
- HighThe component can be taken down completely.
Vector: CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H. Scored by NVD.
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 3.1 | 7.5 | High | NVD |
| CVSS 3.1 | 7.5 | High | CISA (ADP) |
| CVSS 2.0 | 4.6 | Medium | NVD |
Official 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: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Improper Neutralization of Special Elements in Output Used by a Downstream Component
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.
How developers prevent this class of flaw
- Programming languages and supporting technologies might be chosen which are not subject to these issues.
- Utilize an appropriate mix of allowlist and denylist parsing to filter control-plane syntax from all input.
Timeline
- CVE record published.
- Added to CISA's Known Exploited Vulnerabilities catalogue.
- Deadline for US federal agencies to remediate, set by CISA.
- CISA published its SSVC assessment (exploitation: active, automatable: no, technical impact: total).
- Record last changed materially (score, affected products, status or references).
References
Advisories
- issues.apache.org/jira/browse/SOLR-13971Exploit, Issue Tracking
Third-party and government advisories
- oracle.com/security-alerts/cpuoct2020.htmlThird Party Advisory
- cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2019-17558US Government Resource
Technical write-ups (may include proof of concept)
- packetstormsecurity.com/files/157078/Apache-Solr-8.3.0-Velocity-Template-Remote-Code-Execution.htmlExploit, Third Party Advisory, VDB Entry
- lists.apache.org/thread.html/r5074d814d3a8c75df4b20e66bfd268ee0a73ddea7e85070cec3ae78d%40%3Cissues.lucene.apa…Exploit, Mailing List
- lists.apache.org/thread.html/rf6d7ffae2b940114324e036b6394beadf27696d051ae0c4a5edf07af%40%3Cissues.lucene.apa…Exploit, Mailing List
Other references
- lists.apache.org/thread.html/r0b7b9d4113e6ec1ae1d3d0898c645f758511107ea44f0f3a1210c5d5%40%3Cissues.lucene.apa…Mailing List
- lists.apache.org/thread.html/r12ab2cb15a34e49b4fecb5b2bdd7e10f3e8b7bf1f4f47fcde34d3a7c%40%3Cissues.lucene.apa…Mailing List
- lists.apache.org/thread.html/r19d23e8640236a3058b4d6c23e5cd663fde182255f5a9d63e0606a66%40%3Cdev.lucene.apache…Mailing List
- lists.apache.org/thread.html/r1d4a247329a8478073163567bbc8c8cb6b49c6bfc2bf58153a857af1%40%3Ccommits.druid.apa…Mailing List
- lists.apache.org/thread.html/r204ba2a9ea750f38d789d2bb429cc0925ad6133deea7cbc3001d96b5%40%3Csolr-user.lucene…Mailing List
- lists.apache.org/thread.html/r25f1bd4545617f5b86dde27b4c30fec73117af65598a30e20209739a%40%3Cissues.lucene.apa…Mailing List
- lists.apache.org/thread.html/r339865b276614661770c909be1dd7e862232e3ef0af98bfd85686b51%40%3Cdev.lucene.apache…Issue Tracking, Mailing List
- lists.apache.org/thread.html/r36e35fd76239a381643555966fb3e72139e018d52d76544fb42f96d8%40%3Cissues.lucene.apa…Issue Tracking, Mailing List
- lists.apache.org/thread.html/r58c58fe51c87bc30ee13bb8b4c83587f023edb349018705208e65b37%40%3Cissues.lucene.apa…Mailing List
- lists.apache.org/thread.html/r5dc200f7337093285bac40e6d5de5ea66597c3da343a0f7553f1bb12%40%3Csolr-user.lucene…Mailing List
- lists.apache.org/thread.html/r79c7e75f90e735fd32c4e3e97340625aab66c09dfe8c4dc0ab768b69%40%3Csolr-user.lucene…Mailing List
- lists.apache.org/thread.html/r7b89b3dcfc1b6c52dd8d610b897ac98408245040c92b484fe97a51a2%40%3Csolr-user.lucene…Mailing List
- lists.apache.org/thread.html/r7f21ab40a9b17b1a703db84ac56773fcabacd4cc1eb5c4700d17c071%40%3Cissues.lucene.apa…Mailing List
- lists.apache.org/thread.html/r8a36e4f92f4449dec517e560e1b55639f31b3aca26c37bbad45e31de%40%3Cissues.lucene.apa…Mailing List
- lists.apache.org/thread.html/r8e7a3c253a695a7667da0b0ec57f9bb0e31f039e62afbc00a1d96f7b%40%3Csolr-user.lucene…Mailing List
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