CVE-2021-44521Remote code execution for scripted UDFs
- 9.1CriticalCVSS base score
- 58.9%Exploitation in 30 daysEPSS · top 0.9% of all CVEs
- NoKnown exploitednot in CISA's KEV catalog
- 1Public exploitsMetasploit, Nuclei and Exploit-DB
Description
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.
Public exploit
An exploit or proof of concept is public: anyone can try it against an unpatched system. The public collections list a Nuclei template for it.
Show the exploits1
Nuclei templates1 template
- Apache Cassandra Load UDF RCE (Nuclei template) (opens in a new tab)
network/cves/2021/CVE-2021-44521.yamlSeverity critical
Modules, templates and exploits as listed by the Metasploit Framework (BSD-3-Clause), ProjectDiscovery's Nuclei templates (MIT) and the Exploit Database (GPLv2), read once a day. Where the data comes from
Timeline
ID reserved
By apache
- 2 months later
· 2 months later
Published
- 2 years later
· 2 years later
Record updated
Changes after publication (a new score, a public exploit, EPSS crossing 1, 10 or 50 %, leaving KEV) are kept since November 2026; earlier ones are not known.
Scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| NVDNVD · Modified | 3.1 | Critical9.1 | CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H |
- EPSS (exploitation in 30 days)
- 58.9% · top 0.9% of all CVEs (13 Nov 2026)
The list uses the assigner's score when there is one, then CISA's, then NVD's: Critical 9.1.
Affected products
Apache Software Foundation · Apache Cassandra
- affected 3.0.0 – < unspecified
- affected unspecified – < 3.0.26
- affected 3.1 – < unspecified
- affected unspecified – < 3.11.12
- affected 4.0.0 – < unspecified
- affected unspecified – < 4.0.2
Affected packages
From reviewed advisories of the GitHub Advisory Database.
- Mavenorg.apache.cassandra:cassandra-allGHSA-8ffc-79xg-29w8 (opens in a new tab)
What to do
Workaround: Set `enable_user_defined_functions_threads: true` (this is default) or 3.0 users should upgrade to 3.0.26 3.11 users should upgrade to 3.11.12 4.0 users should upgrade to 4.0.2
References
References4
- https://lists.apache.org/thread/y4nb9s4co34j8hdfmrshyl09lokm7356 (opens in a new tab)x_refsource_MISCx_transferred
- [oss-security] 20220211 CVE-2021-44521: Apache Cassandra: Remote code execution for scripted UDFs (opens in a new tab)mailing-listx_refsource_MLISTx_transferred
- https://jfrog.com/blog/cve-2021-44521-exploiting-apache-cassandra-user-defined-functions-for-remote-code-execution/ (opens in a new tab)x_refsource_MISCx_transferred
- https://security.netapp.com/advisory/ntap-20220225-0001/ (opens in a new tab)x_refsource_CONFIRMx_transferred
Sources
The same CVE in the primary databases and aggregators, to check against.
- CVE.org record (opens in a new tab)
- CVE List JSON (GitHub) (opens in a new tab)
- NVD (opens in a new tab)
- FIRST EPSS (opens in a new tab)
- EUVD EUVD-2022-0915 (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisory GHSA-8ffc-79xg-29w8 (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
Badge for a README or a ticket
[](https://cveledger.app/cve/CVE-2021-44521)Record last updated .