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CVE-2009-0021

5.0 · MEDIUM

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 cer…

Published Jan 7, 2009ntpCWE-287EPSS 3.22%

Overview

CVE-2009-0021 is a medium-severity vulnerability affecting ntp ntp. It was published on January 7, 2009 and has a CVSS 2.0 base score of 5.0 (MEDIUM).

This vulnerability has a CVSS 2.0 base score of 5.0, rated MEDIUM. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.

Technical 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.

Remediation

Check the references section for vendor advisories and patches from ntp. Update ntp to the latest patched version. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

Affected products

VendorProductVersionsStatus
ntpntp0Affected

References

Reflists.apple.com/archives/security-announce/2009/May/msg00002.htmlReflists.opensuse.org/opensuse-security-announce/2009-03/msg00000.htmlReflists.opensuse.org/opensuse-security-announce/2009-04/msg00003.htmlRefsecunia.com/advisories/33406Refsecunia.com/advisories/33558Refsecunia.com/advisories/33648Refsecunia.com/advisories/34642Refsecunia.com/advisories/35074Refslackware.com/security/viewer.php?l=slackware-security&y=2009&m=slackware-security.531177Refsupport.apple.com/kb/HT3549

How CyberStrike helps

Frequently asked questions

What is CVE-2009-0021?

CVE-2009-0021 is a medium-severity vulnerability affecting ntp ntp. It was published on January 7, 2009 and has a CVSS 2.0 base score of 5.0 (MEDIUM).

How severe is CVE-2009-0021?

This vulnerability has a CVSS 2.0 base score of 5.0, rated MEDIUM. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.

How do I fix or remediate CVE-2009-0021?

Check the references section for vendor advisories and patches from ntp. Update ntp to the latest patched version. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

How can CyberStrike help with CVE-2009-0021?

CyberStrike is an open-source, AI-augmented pentesting engine. Rather than flag a version number, it tests whether an issue like CVE-2009-0021 is actually reachable in your own applications and APIs, then verifies each finding before reporting it. That tells you if the weakness is a real, exploitable risk in your environment or a false positive you can safely deprioritize.

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