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CVE-2017-17439

In Heimdal through 7.4, remote unauthenticated attackers are able to crash the KDC by sending a...

7.5 HighFix available

CVE-2017-17439 is a high vulnerability (CVSS 7.5) in Heimdal Project Heimdal, published December 6, 2017. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 3.43%, the 88th percentile. Fixed in heimdal 7.4.0-r2.

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.

Attack profile

How easy it is to exploit

Attack vector
Network
Complexity
Low
Privileges needed
None
User interaction
None

What an attacker can affect

Confidentiality
None
Integrity
None
Availability
High

Exploit likelihood

3.43%Up 1.3 points since Apr 14, 2021
90%50%10%1%

What each source reports

NVD Score used 7.5

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.

Record
CVE-2017-17439
CVSS 3.0
7.5 HighCVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
CVSS 2.0
5.0 MediumAV:N/AC:L/Au:N/C:N/I:N/A:P
Weakness
CWE-476
Updated
2026-11-02
CVE List No score

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.

Record
CVE-2017-17439
Updated
2026-11-02
EUVDEUVD-2017-8603 No score

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.

Record
EUVD-2017-8603
Updated
2026-11-03
GitHub AdvisoriesGHSA-gc5p-r2vh-qc88 7.5

In Heimdal through 7.4, remote unauthenticated attackers are able to crash the KDC by sending a...

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.

Record
GHSA-gc5p-r2vh-qc88
CVSS 3.0
7.5 HighCVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Weakness
CWE-476
Updated
2026-11-02
OSVALPINE-CVE-2017-17439 7.5

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.

Record
ALPINE-CVE-2017-17439
CVSS 3.0
7.5 HighCVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Updated
2026-11-02
OSVBELL-CVE-2017-17439 7.5

CVE-2017-17439 does not affect BellSoft software

Record
BELL-CVE-2017-17439
CVSS 3.0
7.5 HighCVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Updated
2026-11-02
Show 5 moreShow less
OSV 7.5

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.

Record
CVE-2017-17439
CVSS 3.0
7.5 HighCVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Updated
2026-11-02
OSVDEBIAN-CVE-2017-17439 7.5

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.

Record
DEBIAN-CVE-2017-17439
CVSS 3.0
7.5 HighCVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Updated
2026-11-02
OSVUBUNTU-CVE-2017-17439 7.5

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.

Record
UBUNTU-CVE-2017-17439
CVSS 3.0
7.5 HighCVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Updated
2026-11-02
OSVMGASA-2017-0485 No score

Updated heimdal packages fix security vulnerability

Michael Eder and Thomas Kittel discovered that Heimdal did not correctly handle ASN.1 data. This would allow an unauthenticated remote attacker to cause a denial of service (crash of the KDC daemon) by sending maliciously crafted packets (CVE-2017-17439).

Record
MGASA-2017-0485
Updated
2026-11-02
OSVopenSUSE-SU-2024:10946-1 No score

libheimdal-7.7.0-1.11 on GA media

These are all security issues fixed in the libheimdal-7.7.0-1.11 package on the GA media of openSUSE Tumbleweed.

Record
openSUSE-SU-2024:10946-1
Updated
2026-11-02

Affected products

Affected packages

Affected packages
PackageAffectedFixed
heimdal
Alpine:v3.10
 before 7.4.0-r2
7.4.0-r2
heimdal
Alpine:v3.11
 before 7.4.0-r2
7.4.0-r2
heimdal
Alpine:v3.12
 before 7.4.0-r2
7.4.0-r2
heimdal
Alpine:v3.13
 before 7.4.0-r2
7.4.0-r2
heimdal
Alpine:v3.14
 before 7.4.0-r2
7.4.0-r2
heimdal
Alpine:v3.15
 before 7.4.0-r2
7.4.0-r2
heimdal
Alpine:v3.16
 before 7.4.0-r2
7.4.0-r2
heimdal
Alpine:v3.17
 before 7.4.0-r2
7.4.0-r2
heimdal
Alpine:v3.18
 before 7.4.0-r2
7.4.0-r2
heimdal
Alpine:v3.19
 before 7.4.0-r2
7.4.0-r2
Show 14 moreShow less
Affected packages
PackageAffectedFixed
heimdal
Alpine:v3.20
 before 7.4.0-r2
7.4.0-r2
heimdal
Alpine:v3.21
 before 7.4.0-r2
7.4.0-r2
heimdal
Alpine:v3.22
 before 7.4.0-r2
7.4.0-r2
heimdal
Alpine:v3.23
 before 7.4.0-r2
7.4.0-r2
heimdal
Alpine:v3.24
 before 7.4.0-r2
7.4.0-r2
heimdal
Alpine:v3.6
 before 7.1.0-r2
7.1.0-r2
heimdal
Alpine:v3.7
 before 7.4.0-r2
7.4.0-r2
heimdal
Alpine:v3.8
 before 7.4.0-r2
7.4.0-r2
heimdal
Alpine:v3.9
 before 7.4.0-r2
7.4.0-r2
heimdal
Debian:12
 before 7.5.0+dfsg-1
7.5.0+dfsg-1
heimdal
Debian:13
 before 7.5.0+dfsg-1
7.5.0+dfsg-1
heimdal
Debian:14
 before 7.5.0+dfsg-1
7.5.0+dfsg-1
heimdal
Debian:9
 before 7.1.0+dfsg-13+deb9u2, plus listed versions
7.1.0+dfsg-137.1.0+dfsg-13+deb9u1
7.1.0+dfsg-13+deb9u2
heimdal
Mageia:6
 before 7.3.0-1.2.mga6
7.3.0-1.2.mga6

History

History
WhenChangedSources
2026-11-03affected
2026-11-03aliasesEUVD
2026-11-02createdCVE List, GitHub Advisories, NVD, OSV

References

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