#VU33177 NULL pointer dereference in heimdal - CVE-2017-17439
Published: December 6, 2017 / Updated: August 3, 2020
Vulnerability identifier: #VU33177
Vulnerability risk: Medium
CVSSv4.0: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U/U:Green
CVE-ID: CVE-2017-17439
CWE-ID: CWE-476
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerable software:
heimdal
heimdal
Software vendor:
Heimdal Software
Heimdal Software
Description
The vulnerability allows a remote non-authenticated attacker to perform a denial of service (DoS) attack.
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
Install update from vendor's website.
External links
- 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