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CVE-2017-17439

7.5 · HIGH

In Heimdal through 7.4, remote unauthenticated attackers are able to crash the KDC by sending a crafted UDP packet containing empty data fields for client name or realm.

Published Dec 6, 2017CWE-476EPSS 3.43%

Overview

CVE-2017-17439 is a high-severity vulnerability. It was published on December 6, 2017 and has a CVSS 3.0 base score of 7.5 (HIGH).

This vulnerability has a CVSS 3.0 base score of 7.5, rated HIGH. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.

Technical description

In Heimdal through 7.4, remote unauthenticated attackers are able to crash the KDC by sending a crafted UDP packet containing empty data fields for client name or realm. The parser would unconditionally dereference NULL pointers in that case, leading to a segmentation fault. This is related to the _kdc_as_rep function in kdc/kerberos5.c and the der_length_visible_string function in lib/asn1/der_length.c.

Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. 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.

References

Refh5l.org/advisories.html?show=2017-12-08Refwww.h5l.org/pipermail/heimdal-announce/2017-December/000008.htmlRefwww.h5l.org/pipermail/heimdal-discuss/2017-August/000259.htmlRefbugs.debian.org/cgi-bin/bugreport.cgi?bug=878144GitHubgithub.com/heimdal/heimdal/commit/1a6a6e462dc2ac6111f9e02c6852ddec4849b887GitHubgithub.com/heimdal/heimdal/issues/353Refwww.debian.org/security/2017/dsa-4055Refh5l.org/advisories.html?show=2017-12-08Refwww.h5l.org/pipermail/heimdal-announce/2017-December/000008.htmlRefwww.h5l.org/pipermail/heimdal-discuss/2017-August/000259.html

How CyberStrike helps

Frequently asked questions

What is CVE-2017-17439?

CVE-2017-17439 is a high-severity vulnerability. It was published on December 6, 2017 and has a CVSS 3.0 base score of 7.5 (HIGH).

How severe is CVE-2017-17439?

This vulnerability has a CVSS 3.0 base score of 7.5, rated HIGH. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.

How do I fix or remediate CVE-2017-17439?

Check the references section for vendor advisories, patches, and mitigation guidance. 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-2017-17439?

CyberStrike is an open-source, AI-augmented pentesting engine. Rather than flag a version number, it tests whether an issue like CVE-2017-17439 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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