Description
decode_sequence_of() in lib/krb5/asn.1/asn1_encode.c in MIT Kerberos 5 (aka krb5) 1.11 and later grows the decoded element array one entry at a time, which allows remote attackers to cause a denial of service (CPU consumption in the KDC) by sending an unauthenticated AS-REQ or TGS-REQ with a large number of elements in a SEQUENCE OF field over TCP.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| Red Hat | Red Hat Enterprise Linux 10 | — | — |
| Red Hat | Red Hat Enterprise Linux 10.2 Extended Update Support | — | — |
| Red Hat | Red Hat Enterprise Linux 9 | — | — |
| Red Hat | Red Hat Enterprise Linux 9.8 Extended Update Support | — | — |
| Red Hat | Red Hat Enterprise Linux 6 | — | — |
| Red Hat | Red Hat Enterprise Linux 7 | — | — |
| Red Hat | Red Hat Enterprise Linux 8 | — | — |
| Red Hat | Red Hat Hardened Images | — | — |
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 | No fix yet | — |
| Debian 13 | krb5 | No fix yet | — |
| Debian 12 | krb5 | No fix yet | — |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 26.10 | krb5 | No fix yet | — |
| Ubuntu 26.04 LTS | krb5 | No fix yet | — |
| Ubuntu 24.04 LTS | krb5 | No fix yet | — |
| Ubuntu 22.04 LTS | krb5 | No fix yet | — |
| Ubuntu 20.04 LTS | krb5 | No fix yet | — |
Show 3 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu Pro 18.04 LTS | krb5 | No fix yet | — |
| Ubuntu Pro 16.04 LTS | krb5 | No fix yet | — |
| Ubuntu Pro 14.04 LTS | krb5 | No fix yet | — |
Alpine
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Alpine v3.24 | krb5 | 1.22.3-r0 | — |
| Alpine v3.23 | krb5 | 1.22.3-r0 | — |
Advisories 1
- WID-SEC-2026-4435 MIT Kerberos: Mehrere Schwachstellen BSI CERT-Bund (WID) · Nov 12, 2026
References
- RHSA-2026:99624 vendor-advisory
- RHSA-2026:99625 vendor-advisory
- RHSA-2026:99715 vendor-advisory
- RHSA-2026:99716 vendor-advisory
- https://access.redhat.com/security/cve/CVE-2026-119079 vdb-entry
- RHBZ#2479231 issue-tracking