CVE-2017-17439

MEDIUM

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.

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

Details

Source: MITRE

Published: 2017-12-06

Updated: 2017-12-30

Type: CWE-476

Risk Information

CVSS v2.0

Base Score: 5

Vector: (AV:N/AC:L/Au:N/C:N/I:N/A:P)

Impact Score: 2.9

Exploitability Score: 10

Severity: MEDIUM

CVSS v3.0

Base Score: 7.5

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

Impact Score: 3.6

Exploitability Score: 3.9

Severity: HIGH