CVE-2021-44521

CRITICALNVD 9.19.1—
EchelonGraph scoreMEDIUM confidence

This critical-severity CVE scores 9.1 under NVD CVSS v3. EPSS exploit probability: 54.7%, top 1% of all CVEs by exploit prediction. GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).

Triggered by: NVD CVSS baseline
Sources: epss, nvd
Trending — 3 sources updated this weekElevated
9.1
EchelonGraph verdictPatch this weekExploitation is likely or a public exploit exists.
  • High exploitation likelihood — EPSS 55%
CISA-KEV: Not listedEPSS: 55%CVSS: 9.1Exploit: NoneExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

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.

CVSS v3
9.1
EG Score
9.1(medium)
EG Risk
67(Track*)
EG Risk 67/100SSVC: Track*

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity91% × 45%
Exploitation55% × 40%
Automatability30% × 15%
Action: Watch closely — could escalate to Attend.
EPSS
98.9%
KEV
Not listed

Published

February 11, 2022

Last Modified

November 21, 2024

Advisory Details (3)

Auto-updated Jul 21, 2026
No patch confirmed yet.
generic

NetApp Product Security

https://security.netapp.com/advisory/ntap-20220225-0001/
generic
https://lists.apache.org/thread/y4nb9s4co34j8hdfmrshyl09lokm7356
generic

oss-security - CVE-2021-44521: Apache Cassandra: Remote code execution for scripted UDFs

http://www.openwall.com/lists/oss-security/2022/02/11/4

Affected Packages

(1 across 1 ecosystem)
Maven(1)
PackageVulnerable rangeFixed inDependents
org.apache.cassandra:cassandra-all4.0.0, 4.0.14.0.2—

Weakness Classification(2)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 11× in last 7d / 36× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

  1. 2026-07-23 02:05 UTCEG score recompute
  2. 2026-07-22 22:51 UTCEG score recompute
  3. 2026-07-22 14:06 UTCEPSS rescore
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  1. 2026-06-30 23:20 UTCEPSS rescore
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  3. 2026-06-29 20:53 UTCOSV refresh
  4. 2026-06-27 03:06 UTCEPSS rescore
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  24. 2026-06-12 23:10 UTCEPSS rescore
  25. 2026-06-12 09:10 UTCOSV refresh
  26. 2026-06-11 13:58 UTCEPSS rescore
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  28. 2026-06-10 22:16 UTCEPSS rescore
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  30. 2026-06-05 06:09 UTCEPSS rescore
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  41. 2026-05-26 03:14 UTCEG score recompute
  42. 2026-05-23 23:53 UTCOSV refresh

Publicly available exploits

(1 reference)

Working exploit code is in the public domain. Defenders should treat patch urgency accordingly — public PoCs typically lead to mass-exploitation within 24-72 hours.

  • Nucleinetwork/cves/2021/CVE-2021-44521.yaml
    First seen Jan 1, 2021

    Apache Cassandra Load UDF RCE

    Open source ↗

Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2021-44521?
CVE-2021-44521 is a critical vulnerability published on February 11, 2022. When running Apache Cassandra with the following configuration: enableuserdefinedfunctions: true enablescripteduserdefinedfunctions: true enableuserdefinedfunctions_threads: false it is possible for an attacker to execute arbitrary code on the host. The attacker would need to have enough…
When was CVE-2021-44521 disclosed?
CVE-2021-44521 was first published in the National Vulnerability Database on February 11, 2022, with the most recent update on November 21, 2024. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2021-44521 actively exploited?
CVE-2021-44521 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 98.9% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2021-44521?
CVE-2021-44521 has a CVSS v3 base score of 9.1 (NVD).
How do I remediate CVE-2021-44521?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2021-44521, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

Dependency Blast Radius

See which npm, PyPI, Go, and Maven packages are affected by CVE-2021-44521

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