CVE-2021-31522

Arbitrary class loading via unvalidated query parameters

Published Jan 6, 2022 · Updated Aug 3, 2024

Unsafe reflection in Apache Kylin allows remote authenticated users to load arbitrary Java classes through crafted SQL parameter metadata. QueryService.setParam passes the request-supplied className directly to Class.forName instead of restricting it to JDBC representation classes. The query API requires authentication, and the resulting behavior is limited to classes already present on the server classpath.

CVSS severity9.8
Critical
EPSS probability2.90%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Unsafe reflection in Apache Kylin allows remote authenticated users to load arbitrary Java classes through crafted SQL parameter metadata. QueryService.setParam passes the request-supplied className directly to Class.forName instead of restricting it to JDBC representation classes. The query API requires authentication, and the resulting behavior is limited to classes already present on the server classpath.

The record

CVE
CVE-2021-31522
Published
Jan 6, 2022
Updated
Aug 3, 2024
Vendor
The Apache Software Foundation
Product
Apache Kylin
Classifications
CWE-470, CAPEC-138
Attack vector
Unavailable
Privileges
Unavailable

Timeline

How it unfolded

  1. Jan 6, 2022CVE publishedPublication date reported by the CVE source.
  2. Aug 3, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=Apache Kylin 2 <=2.6.6
  2. Affected versionversion=Apache Kylin 3 <=3.1.2
  3. Affected versionversion=Apache Kylin 4 <=4.0.0

What conditions does exploitation require?

Attack vectorUnavailable in this record.
Required privilegesUnavailable in this record.

What is affected?

The Apache Software Foundation · Apache Kylinversion=Apache Kylin 2 <=2.6.6; version=Apache Kylin 3 <=3.1.2; version=Apache Kylin 4 <=4.0.0

Published CVSS scores

9.8NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
7.5NIST NVDAV:N/AC:L/Au:N/C:P/I:P/A:P

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
VectorUnavailable
PrivilegesUnavailable
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-470Use of Externally-Controlled Input to Select Classes or Code ('Unsafe Reflection')
CAPEC-138Reflection Injection

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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