Is CVE-2009-0021 in the CISA KEV catalog?

No. CVE-2009-0021 is not currently on the CISA Known Exploited Vulnerabilities list.

What is the CVSS severity of CVE-2009-0021?

CVE-2009-0021 has a CVSS v2 base score of 5.0 (MEDIUM).

What is the EPSS score for CVE-2009-0021?

CVE-2009-0021 has an EPSS score of 3.22% (87th percentile), estimating the probability of exploitation in the next 30 days.

How do I fix CVE-2009-0021?

Upgrade ntp on debian 11 to 1:4.2.4p4+dfsg-8 or later.

CVE & CISA-KEV Catalog

CVE-2009-0021

MEDIUMEPSS 87th pctl

5.0

CVSS v2

NVD

Description

NTP 4.2.4 before 4.2.4p5 and 4.2.5 before 4.2.5p150 does not properly check the return value from the OpenSSL EVP_VerifyFinal function, which allows remote attackers to bypass validation of the certificate chain via a malformed SSL/TLS signature for DSA and ECDSA keys, a similar vulnerability to CVE-2008-5077.

CWE-287Improper Authentication

How to fix

Remediation Available

ntpDebian

Fixed in:1:4.2.4p4+dfsg-8CVE-2009-0021

Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.

CVSS v2 Vector

No CVSS vector data available.

Exploit Intelligence

3.22%probability of exploitation in 30 days

87thpercentile

Elevated risk: more likely to be exploited than 87% of all known CVEs.

References

Vendor Advisory7

Government Resource1

us-cert.gov

Other references11

Related Vulnerabilities

Other CWE-287 (Improper Authentication) vulnerabilities, ordered by exploit likelihood. View all

CVE	Severity	CVSS	EPSS	Exploited	Fix
CVE-2023-35082	Critical	9.8	100%	KEV + Ransom	Fix
CVE-2023-35078	Critical	9.8	100%	KEV + Ransom	Fix
CVE-2017-7921	Critical	9.8	100%	KEV	-
CVE-2024-7593	Critical	9.8	100%	KEV	-
CVE-2023-46805	High	8.2	100%	KEV + Ransom	-
CVE-2022-40684	Critical	9.8	100%	KEV + Ransom	Fix

Embed a live status badge for CVE-2009-0021

Markdown

[![CVE-2009-0021](https://tridentstack.com/cve/badge/CVE-2009-0021.svg)](https://tridentstack.com/cve/CVE-2009-0021)

HTML

<a href="https://tridentstack.com/cve/CVE-2009-0021"><img src="https://tridentstack.com/cve/badge/CVE-2009-0021.svg" alt="CVE-2009-0021"></a>

Find and fix vulnerabilities across your fleet

TridentStack Control continuously scans your Windows, macOS, and Linux fleet for known vulnerabilities, prioritizes them by severity and active exploitation, and patches them automatically.

Start free

This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-04-23.