CVE-2017-17439: Null Pointer Dereference
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 kdcasrep function in kdc/kerberos5.c and the derlengthvisiblestring function in lib/asn1/derlength.c.
Affected Software
Remediation
Patch Available
Event History
Frequently Asked Questions
What is the severity of CVE-2017-17439?
CVE-2017-17439 has a severity rating that indicates it allows remote unauthenticated attackers to crash the KDC.
How do I fix CVE-2017-17439?
To fix CVE-2017-17439, upgrade Heimdal to version 7.5.0 or later.
Which versions of Heimdal are affected by CVE-2017-17439?
Heimdal versions up to and including 7.4 are affected by CVE-2017-17439.
What type of attacks does CVE-2017-17439 facilitate?
CVE-2017-17439 facilitates denial-of-service attacks by crashing the KDC via crafted UDP packets.
Can CVE-2017-17439 be exploited without authentication?
Yes, CVE-2017-17439 can be exploited by remote unauthenticated attackers.