CVE-2017-17439

high

Published 2017-12-06 · Modified 2026-05-13

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CVSS v3

7.5

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

CVSS v4 NEW

—

not yet in upstream

VIR risk

7.5

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.

Predictions

Exploit likelihood

83%

Patch ETA

—

Heuristic predictions, AS-IS, for prioritization only.

Mitigations

No mitigations published for this CVE yet.

The vendor-content worker queues fetches as references arrive (check back in a few minutes). Or — if you've already worked around this in production — publish your fix to the community-verified tier.

✚ Propose a mitigation on Community → Mitigations published via the community go through AI scoring + 2 human reviewers + 7-day silent objection window before landing here with source_tier=community-verified.

OS impact

OS	Version	Status	Fixed in
debian	bookworm	fixed	`7.5.0+dfsg-1`
debian	bullseye	fixed	`7.5.0+dfsg-1`
debian	forky	fixed	`7.5.0+dfsg-1`
debian	sid	fixed	`7.5.0+dfsg-1`
debian	trixie	fixed	`7.5.0+dfsg-1`
debian	9.0	affected

Application impact

Vendor	Product	Versions	Fixed
heimdal_project	heimdal	`{"endIncluding":"7.4.0"}`

References

CWEs

CWE-476

Community-verified mitigations for this CVE will appear above when contributors publish them.

Verify integrity in audit chain (admin only). AS-IS.