CVE-2017-17439 Information

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.

CVSS Vector

CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Reference

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

Attack Complexity

LOW

Privileges Required

NONE

User Interaction Required

NONE

Scope

NONE

Confidentiality Impact

UNCHANGED

Integrity Impact

NONE

Availability Impact

NONE

Base Score

HIGH

Base Severity

7.5