Is CVE-2017-17439 in the CISA KEV catalog?

No. CVE-2017-17439 is not currently on the CISA Known Exploited Vulnerabilities list.

What is the CVSS severity of CVE-2017-17439?

CVE-2017-17439 has a CVSS v3 base score of 7.5 (HIGH).

What is the EPSS score for CVE-2017-17439?

CVE-2017-17439 has an EPSS score of 3.43% (87th percentile), estimating the probability of exploitation in the next 30 days.

How do I fix CVE-2017-17439?

Upgrade heimdal on debian 11 to 7.5.0+dfsg-1 or later.

CVE & CISA-KEV Catalog

CVE-2017-17439

HIGHEPSS 87th pctl

7.5

CVSS v3

NVD

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.

CWE-476NULL Pointer Dereference

How to fix

Remediation Available

heimdalDebian

Fixed in:7.5.0+dfsg-1CVE-2017-17439

Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.

CVSS v3 Vector

Exploitability

Attack VectorNetwork

Attack ComplexityLow

Privileges RequiredNone

User InteractionNone

ScopeUnchanged

Impact

ConfidentialityNone

IntegrityNone

AvailabilityHigh

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

Exploit Intelligence

3.43%probability of exploitation in 30 days

87thpercentile

Elevated risk: more likely to be exploited than 87% of all known CVEs.

References

Patch1

github.com

Third-Party Advisory4

Other references2

Related Vulnerabilities

Other CWE-476 (NULL Pointer Dereference) vulnerabilities, ordered by exploit likelihood. View all

CVE	Severity	CVSS	EPSS	Exploited	Fix
CVE-2023-21758	High	7.5	92%	-	Fix
CVE-2023-21547	High	7.5	88%	-	Fix
CVE-2014-3470	Medium	4.3	86%	-	Fix
CVE-2021-44224	High	8.2	82%	-	Fix
CVE-2016-0742	High	7.5	82%	-	Fix
CVE-2009-1386	Medium	5.0	80%	-	Fix

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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-05-13.