CVE-2017-17439
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.
Does this matter?
High impact if exploited, but EPSS currently rates exploitation as unlikely (3.43%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.
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 3.0
- 7.5 HIGHCVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- EPSS
- 3.43% probability · 89th percentile
- Public exploits
- None in Exploit-DB
- CISA KEV
- Not listed
- Weakness
- CWE-476
- Affected
- debian/debian linux · heimdal project/heimdal
- Source
- cve@mitre.org
EPSS 3.4% since 27 October 2026; no change recorded yet. Points are recorded when the score first appears and whenever it moves by a percentage point or more.
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.htmlThird Party Advisory
- https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=878144Issue Tracking, Mailing List, Third Party Advisory
- https://github.com/heimdal/heimdal/commit/1a6a6e462dc2ac6111f9e02c6852ddec4849b887Third Party Advisory
- https://github.com/heimdal/heimdal/issues/353Patch, Third Party Advisory
- https://www.debian.org/security/2017/dsa-4055Third Party Advisory
- 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.htmlThird Party Advisory
- https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=878144Issue Tracking, Mailing List, Third Party Advisory
- https://github.com/heimdal/heimdal/commit/1a6a6e462dc2ac6111f9e02c6852ddec4849b887Third Party Advisory
- https://github.com/heimdal/heimdal/issues/353Patch, Third Party Advisory
- https://www.debian.org/security/2017/dsa-4055Third Party Advisory
Source: NVD record, EPSS from FIRST.org, KEV from CISA, exploits from Exploit-DB. Refreshed daily. Download this record as JSON.