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Fencer Vulns
critical 9.1

CVE-2021-44521 in the critical feed json

Remote code execution for scripted UDFs

published 2022-02-11 4 y ago modified 2026-09-08 2 mo ago also BIT-cassandra-2021-44521 , EUVD-2022-0915 , GHSA-8ffc-79xg-29w8

cvss
9.1
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
57.5%
EPSS 57.5% chance of exploitation in 30 days, percentile 99%
public exploits
0
none known, plus a Nuclei check

Summary

When running Apache Cassandra with the following configuration: enable_user_defined_functions: true enable_scripted_user_defined_functions: true enable_user_defined_functions_threads: false it is possible for an attacker to execute arbitrary code on the host. The attacker would need to have enough permissions to create user defined functions in the cluster to be able to exploit this. Note that this configuration is documented as unsafe, and will continue to be considered unsafe after this CVE.

Patch / fix

  • maven org.apache.cassandra:cassandra-all 3.0.26, 3.11.12, 4.0.2
  • bitnami cassandra 3.0.26, 3.11.12, 4.0.2
  • Apache Software Foundation Apache Cassandra 3.0.26, 3.11.12, 4.0.2

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2021-44521 updated cvss 9.1

cassandra: RCE for scripted UDFs

  • Red Hat Fuse 7 cassandra
    affected: no fix available “Fix deferred”
  • Red Hat JBoss Data Grid 7 cassandra Red Hat JBoss Data Virtualization 6 cassandra Red Hat JBoss Enterprise Application Platform 6 cassandra, jboss-on jboss-on Red Hat JBoss Fuse 6 cassandra Red Hat JBoss Fuse Service Works 6 cassandra Red Hat JBoss Operations Network 3 cassandra, org.jboss.on-jboss-on-parent org.jboss.on-jboss-on-parent
    +2 more products
    Red Hat OpenShift Container Platform 3.11 openshift3/ose-metrics-cassandra, openshift3/ose-metrics-hawkular-metrics, openshift3/ose-metrics-schema-installer Red Hat Openshift Container Storage 4 ocs4/ocs-rhel8-operator, ocs4/ocs-must-gather-rhel8, ocs4/rook-ceph-rhel8-operator, odf-multicluster-operator-container
    affected: no fix planned “Out of support scope”
  • Red Hat Openshift Data Foundation 4 odf4/ocs-rhel9-operator, odf4/ocs-must-gather-rhel8, odf4/rook-ceph-rhel9-operator, odf4/odf-multicluster-rhel9-operator
    affected: no fix planned “Will not fix”
  • Red Hat OpenStack Platform 10 (Newton) opendaylight, puppet-cassandra Red Hat OpenStack Platform 13 (Queens) puppet-cassandra
    affected: no fix planned “Out of support scope”
  • Red Hat A-MQ Clients 2 cassandra, org.apache.logging.log4j-log4j org.apache.logging.log4j-log4j Red Hat Distributed Tracing Jaeger 1 distributed-tracing/jaeger-agent-rhel8, distributed-tracing/jaeger-query-rhel8, distributed-tracing/jaeger-ingester-rhel8, distributed-tracing/jaeger-collector-rhel8, distributed-tracing/jaeger-all-in-one-rhel8, distributed-tracing/jaeger-es-rollover-rhel8, +1 more Red Hat build of Quarkus cassandra Red Hat Data Grid 8 cassandra Red Hat Integration Camel K 1 cassandra Red Hat Integration Camel Quarkus 1 cassandra
    +8 more products
    Red Hat Integration Data Virtualisation Operator cassandra Red Hat JBoss Enterprise Application Platform 7 cassandra Red Hat JBoss Enterprise Application Platform Expansion Pack cassandra Red Hat OpenShift Application Runtimes cassandra Red Hat OpenShift distributed tracing 2 rhosdt/jaeger-agent-rhel8, rhosdt/jaeger-query-rhel8, rhosdt/jaeger-ingester-rhel8, rhosdt/jaeger-collector-rhel8, rhosdt/jaeger-all-in-one-rhel8, rhosdt/jaeger-es-rollover-rhel8, +1 more Red Hat OpenStack Platform 16.1 puppet-cassandra Red Hat OpenStack Platform 16.2 puppet-cassandra Red Hat streams for Apache Kafka cassandra
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

Exploit prediction

57.53% chance of exploitation in the next 30 days, higher than 99% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • Nuclei template Apache Cassandra Load UDF RCE nuclei detection template
  • jfrog.com https://jfrog.com/blog/cve-2021-44521-exploiting-apache-cassandra-user-defined-functions-for-remote-code-execution/ referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
GitHub 3.1 9.1 CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H
NVD 3.1 9.1 CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H
NVD 2.0 8.5 AV:N/AC:M/Au:S/C:C/I:C/A:C
OSV 3.1 9.1 CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H

Affected packages

ecosystem package affected fixed in
maven org.apache.cassandra:cassandra-all
<3.0.26
>=3.11.0, <3.11.12
>=4.0.0, <4.0.2
3.0.26
3.11.12
4.0.2
bitnami cassandra
>=3.0.0, <3.0.26
>=3.11.0, <3.11.12
>=4.0.0, <4.0.2
3.0.26
3.11.12
4.0.2

Affected products

  • Apache Software Foundation Apache Cassandra

Classification

Weakness
  • CWE-94 Improper Control of Generation of Code
  • CWE-732 Incorrect Permission Assignment for Critical Resource

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.