CVE-2017-17439

Name: CVE-2017-17439
Creator: NVD / NIST
Published: 2017-12-06T15:29:00.25+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

UnknownEPSS 3.43%

Last modified Jun 17, 2026

CVE-2017-17439 is a vulnerability of currently unknown severity. 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. EPSS estimates a 3.43% chance of exploitation in the next 30 days.

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.

Metrics

EPSS Probability

3.43%

87.4th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-476

Affected Software

Vendor	Product	Versions
Debian	Debian Linux	9.0
Heimdal Project	Heimdal	<= 7.4.0

References

http://h5l.org/advisories.html?show=2017-12-08
http://www.h5l.org/pipermail/heimdal-announce/2017-December/000008.html
http://www.h5l.org/pipermail/heimdal-discuss/2017-August/000259.htmlThird Party Advisory
https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=878144Issue Tracking, Mailing List, Third Party Advisory
https://github.com/heimdal/heimdal/commit/1a6a6e462dc2ac6111f9e02c6852ddec4849b887Third Party Advisory
https://github.com/heimdal/heimdal/issues/353Patch, Third Party Advisory
https://www.debian.org/security/2017/dsa-4055Third Party Advisory
http://h5l.org/advisories.html?show=2017-12-08
http://www.h5l.org/pipermail/heimdal-announce/2017-December/000008.html
http://www.h5l.org/pipermail/heimdal-discuss/2017-August/000259.htmlThird Party Advisory
https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=878144Issue Tracking, Mailing List, Third Party Advisory
https://github.com/heimdal/heimdal/commit/1a6a6e462dc2ac6111f9e02c6852ddec4849b887Third Party Advisory
https://github.com/heimdal/heimdal/issues/353Patch, Third Party Advisory
https://www.debian.org/security/2017/dsa-4055Third Party Advisory

Timeline

Published: Dec 6, 2017
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2017-17439?

How severe is CVE-2017-17439?

Severity scoring for CVE-2017-17439 is pending analysis. The EPSS model estimates a 3.43% probability of exploitation in the next 30 days.

How do I fix CVE-2017-17439?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2017-17439?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST