Vulnerability CVE-2017-17439
Published: 2017-12-06

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.

Type:

CWE-476

 (NULL Pointer Dereference)

CVSS2 => (AV:N/AC:L/Au:N/C:N/I:N/A:P)

CVSS Base Score
Impact Subscore
Exploitability Subscore
5/10
2.9/10
10/10
Exploit range
Attack complexity
Authentication
Remote
Low
No required
Confidentiality impact
Integrity impact
Availability impact
None
None
Partial
Affected software
Heimdal project -> Heimdal 
Debian -> Debian linux 

 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.html
https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=878144
https://github.com/heimdal/heimdal/commit/1a6a6e462dc2ac6111f9e02c6852ddec4849b887
https://github.com/heimdal/heimdal/issues/353
https://www.debian.org/security/2017/dsa-4055
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