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CRITICAL severity

CVE-2021-31522 — kylin

CRITICALFix: apache/kylin#1695

CVE-2021-31522 is a critical-severity (CVSS 9.8) CWE-470 vulnerability in org.apache.kylin:kylin. A fix is available for org.apache.kylin:kylin — see the affected versions and patch details below.

Kylin can receive user input and load any class through Class.forName(...).

Also known asGHSA-q656-g2x3-8cgh
Published
Updated
Affected
2 pkgs
Patched
2 / 2
Exploits
None indexed
Exploitation data as of Oct 4, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗
2.9%probability of exploitation in next 30 days
Lower Risk0.00%
Lower risk than most CVEs86th percentile — riskier than 86% of all scored CVEsHighest risk
2.40%2.90%3.40%3.90%3.4%2.9%Apr 26Aug 26Oct 26

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

CVE-2021-31522 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.

Where this sits among everything scored

Of 385,386 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Counts from FIRST.org, log-scaled.

Real-World Exposure

2 pkgs affected
☕org.apache.kylin:kylin☕org.apache.kylin:kylin

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects Maven packages — download data is not available via public APIs for these ecosystems.

Description

Kylin can receive user input and load any class through Class.forName(...). This issue affects Apache Kylin 2 version 2.6.6 and prior versions; Apache Kylin 3 version 3.1.2 and prior versions; Apache Kylin 4 version 4.0.0 and prior versions.

Affected Packages

2 total 2 fixed
EcosystemPackageVulnerable rangeFix
☕Mavenorg.apache.kylin:kylinall versions3.1.3org.apache.kylin:kylin:3.1.3
☕Mavenorg.apache.kylin:kylin≥ 4.0.0&&< 4.0.14.0.1org.apache.kylin:kylin:4.0.1

Affected Products

1 product · 5 configurations
Application
kylinapache
≥ 3.0.0 && ≤ 2.6.6
1 version
4.0.0

Detection & mitigation playbook

Open-source dependency

  1. Detect

    Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for org.apache.kylin:kylin, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

  2. Fix

    Update org.apache.kylin:kylin to 3.1.3 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2021-31522 is resolved across your whole dependency graph.

  3. Workarounds

    If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

Frequently Asked Questions

Kylin can receive user input and load any class through Class.forName(...). This issue affects Apache Kylin 2 version 2.6.6 and prior versions; Apache Kylin 3 version 3.1.2 and prior versions; Apache Kylin 4 version 4.0.0 and prior versions.
O3 Security · Impact-Aware SCA

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Find it across Maven, including transitive dependencies.

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CVE-2021-31522: kylin — Fixed in 3.1.3