Description
The validate_as_request function in kdc_util.c in the Key Distribution Center (KDC) in MIT Kerberos 5 (aka krb5) before 1.13.6 and 1.4.x before 1.14.3, when restrict_anonymous_to_tgt is enabled, uses an incorrect client data structure, which allows remote authenticated users to cause a denial of service (NULL pointer dereference and daemon crash) via an S4U2Self request.
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 | krb5 | 1.14.3+dfsg-1 | — |
| Debian 13 | krb5 | 1.14.3+dfsg-1 | — |
| Debian 12 | krb5 | 1.14.3+dfsg-1 | — |
| Debian 7 | krb5 | 1.10.1+dfsg-5+deb7u9 | DLA-1265-1 |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 16.04 LTS | krb5 | 1.13.2+dfsg-5ubuntu2.1 | — |
| Ubuntu 14.04 LTS | krb5 | 1.12+dfsg-2ubuntu5.4 | — |
Red Hat
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| RHEL 7 | krb5 +7 | 1.14.1-26.el7 | RHSA-2016:2591 |
SUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLES 12 SP1 | krb5 | 1.12.1-36.4 | SUSE-SU-2016:2136-1 |
Show 1 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLES for SAP 12 SP1 | krb5 | 1.12.1-36.4 | SUSE-SU-2016:2136-1 |
openSUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| openSUSE Tumbleweed | krb5 | 1.15-1.1 | openSUSE-SU-2024:10004-1 |
Alpine
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Alpine v3.4 | krb5 | 1.14.3-r0 | — |
| Alpine v3.3 | krb5 | 1.14.3-r0 | — |
| Alpine v3.2 | krb5 | 1.13.6-r0 | — |
Oracle Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Oracle Linux 7 | libkadm5 +6 | 1.14.1-26.el7 | ELSA-2016-2591 |
Advisories 5
- RHSA-2016:2591 Red Hat Security Advisory: krb5 security, bug fix, and enhancement update Red Hat Security Advisories (RHSA) · Aug 5, 2026
- DLA-1265-1 krb5 - security update Debian Security (DSA / DLA) · Mar 9, 2026
- openSUSE-SU-2024:10004-1 krb5-1.15-1.1 on GA media SUSE / openSUSE Security Updates · Feb 4, 2026
- SUSE-SU-2016:2136-1 Security update for krb5 SUSE / openSUSE Security Updates · Feb 4, 2026
- ELSA-2016-2591 Low: krb5 security, bug fix, and enhancement update (Oracle Linux 7) Oracle Linux Security Advisories (ELSA) · Nov 9, 2016
References
- https://github.com/krb5/krb5/commit/93b4a6306a0026cf1cc31ac4bd8a49ba5d034ba7
- 92132 vdb-entry
- [debian-lts-announce] 20180131 [SECURITY] [DLA 1265-1] krb5 security update mailing-list
- openSUSE-SU-2016:2268 vendor-advisory
- http://krbdev.mit.edu/rt/Ticket/Display.html?id=8458
- 1036442 vdb-entry
- http://web.mit.edu/kerberos/krb5-1.13/
- RHSA-2016:2591 vendor-advisory
- http://web.mit.edu/kerberos/krb5-1.14/
- FEDORA-2016-0674a3c372 vendor-advisory