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.
Fixed in Linux distributions
Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.
Debian
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian 14 | heimdal | 7.5.0+dfsg-1 | — |
| Debian 13 | heimdal | 7.5.0+dfsg-1 | — |
| Debian 12 | heimdal | 7.5.0+dfsg-1 | — |
| Debian 9 | heimdal | 7.1.0+dfsg-13+deb9u2 | DSA-4055-1 |
Alpine
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Alpine v3.24 | heimdal | 7.4.0-r2 | — |
| Alpine v3.23 | heimdal | 7.4.0-r2 | — |
| Alpine v3.22 | heimdal | 7.4.0-r2 | — |
| Alpine v3.21 | heimdal | 7.4.0-r2 | — |
| Alpine v3.20 | heimdal | 7.4.0-r2 | — |
Show 14 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Alpine v3.19 | heimdal | 7.4.0-r2 | — |
| Alpine v3.18 | heimdal | 7.4.0-r2 | — |
| Alpine v3.17 | heimdal | 7.4.0-r2 | — |
| Alpine v3.16 | heimdal | 7.4.0-r2 | — |
| Alpine v3.15 | heimdal | 7.4.0-r2 | — |
| Alpine v3.14 | heimdal | 7.4.0-r2 | — |
| Alpine v3.13 | heimdal | 7.4.0-r2 | — |
| Alpine v3.12 | heimdal | 7.4.0-r2 | — |
| Alpine v3.11 | heimdal | 7.4.0-r2 | — |
| Alpine v3.10 | heimdal | 7.4.0-r2 | — |
| Alpine v3.9 | heimdal | 7.4.0-r2 | — |
| Alpine v3.8 | heimdal | 7.4.0-r2 | — |
| Alpine v3.7 | heimdal | 7.4.0-r2 | — |
| Alpine v3.6 | heimdal | 7.1.0-r2 | — |
Advisories 1
- DSA-4055-1 heimdal - security update Debian Security (DSA / DLA) · Mar 9, 2026
References
- https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=878144
- https://github.com/heimdal/heimdal/commit/1a6a6e462dc2ac6111f9e02c6852ddec4849b887
- http://www.h5l.org/pipermail/heimdal-announce/2017-December/000008.html
- http://www.h5l.org/pipermail/heimdal-discuss/2017-August/000259.html
- https://github.com/heimdal/heimdal/issues/353
- http://h5l.org/advisories.html?show=2017-12-08
- DSA-4055 vendor-advisory