MIT Kerberos: Mehrere Schwachstellen ermöglichen Denial of Service
WID-SEC-2026-1290 · first 28.04.2026 · updated 15.10.2026 · CVSS 7,5
What it is about
Kerberos ist ein verteilter Netzwerkdienst zur Authentifizierung. MIT Kerberos ist die freie Implementierung des "Kerberos network authentication protocol", des Massachusetts Institute of Technology (MIT). Ein Angreifer kann mehrere Schwachstellen in MIT Kerberos ausnutzen, um einen Denial of Service Angriff durchzuführen.
Under what conditions?
The BSI does not name any particular preconditions. Exploitable remotely according to the BSI.
What can happen in the worst case
An attacker could use the vulnerability to
- einen Denial of Service Angriff durchzuführen
Am I affected?
Affected according to the BSI:
- Red Hat Enterprise Linux
- Fedora Linux
- SUSE Linux
- Oracle Linux
- SUSE openSUSE
- RESF Rocky Linux
- IBM MQ operator
- MIT Kerberos >=1.18
- Siemens SIMATIC S7 1500 CPU
- Debian Linux
- Red Hat Enterprise Linux Cryostat <4.2.0
- Red Hat Enterprise Linux Update Infrastructure 5.1
and 3 more
The installed version is usually shown under “Help → About” or in the device’s admin interface.
What helps?
Update to at least:
- MIT Kerberos >=1.18
- Red Hat Enterprise Linux Cryostat 4.2.0
- IBM QRadar SIEM 7.5.0 UP15 IF04
- Dell Secure Connect Gateway 5.36.00.16
Is the vulnerability already being exploited?
None of the CVEs is in the CISA catalogue of exploited vulnerabilities. That does not mean there are no attacks, only that none are documented.
Information and sources
- Original BSI advisory (WID)
- SUSE Security Update SUSE-SU-2026:22255-1 vom 2026-06-29 lists.suse.com
- Cem's Blog vom 2026-04-27 mit PoC cems.fun
- OSS Security Mailing List vom 2026-04-27 seclists.org
- krb5 Fix vom 2026-04-27 github.com
- Fedora Security Advisory FEDORA-2026-2E9FE57A46 vom 2026-04-29 bodhi.fedoraproject.org
- Fedora Security Advisory FEDORA-2026-8B43EA2F82 vom 2026-04-29 bodhi.fedoraproject.org
- Fedora Security Advisory FEDORA-2026-6C99AAA6D3 vom 2026-04-29 bodhi.fedoraproject.org
- Fedora Security Advisory FEDORA-2026-684396998A vom 2026-04-29 bodhi.fedoraproject.org
- Red Hat Security Advisory RHSA-2026:12220 vom 2026-04-30 access.redhat.com
- SUSE Security Update SUSE-SU-2026:22322-1 vom 2026-07-01 lists.suse.com
- openSUSE Security Update OPENSUSE-SU-2026:10729-1 vom 2026-05-11 lists.opensuse.org
- Red Hat Security Advisory RHSA-2026:16799 vom 2026-05-13 access.redhat.com
- Rocky Linux Security Advisory RLSA-2026:16799 vom 2026-05-14 errata.build.resf.org
- Oracle Linux Security Advisory ELSA-2026-16799 vom 2026-05-15 linux.oracle.com
- SUSE Security Update SUSE-SU-2026:1816-1 vom 2026-05-13 lists.suse.com
- SUSE Security Update SUSE-SU-2026:21629-1 vom 2026-05-15 lists.suse.com
- SUSE Security Update SUSE-SU-2026:21618-1 vom 2026-05-15 lists.suse.com
- SUSE Security Update SUSE-SU-2026:21641-1 vom 2026-05-15 lists.suse.com
- Red Hat Security Advisory RHSA-2026:19357 vom 2026-05-20 access.redhat.com
- Red Hat Security Advisory RHSA-2026:19145 vom 2026-05-19 access.redhat.com
- Debian Security Advisory DSA-6293 vom 2026-05-23 security-tracker.debian.org
- Red Hat Security Advisory RHSA-2026:17789 vom 2026-05-26 access.redhat.com
- Red Hat Security Advisory RHSA-2026:21275 vom 2026-05-27 access.redhat.com
- Debian Security Advisory DLA-4603 vom 2026-05-28 lists.debian.org
- Red Hat Security Advisory RHSA-2026:22634 vom 2026-06-02 access.redhat.com
and 16 more sources in the original advisory
CVE: CVE-2026-40355, CVE-2026-40356
Source: BSI warning and information service (CERT-Bund); CISA. The assessment of the conditions is my reading of the BSI text; the external pages are in their original language.