Red Hat

CVE-2026-119079: Krb5: mit krb5 kdc unauthenticated cpu dos via quadratic asn.1 sequence of decoding

Is it exploited?

Not on CISA's list. CISA has not added it to the Known Exploited Vulnerabilities catalog as of 10 Nov 2026. If CISA adds it, this page shows it as known exploited.

How likely is exploitation in the next 30 days?

0.6%

EPSS score, percentile 51.1 of all scored records. A probability estimated by FIRST, not a report of exploitation.

How severe?

7.5 High

CVSS v3.1 base score, given by the CNA

What should I do?

CISA has set no required action, because the vulnerability is not in KEV.

No patch or vendor advisory is listed in the CVE record. Check Red Hat's advisories.

Which versions are affected?

Versions by product

Source: CISA KEV 2026.11.10, as of 10 Nov 2026; FIRST EPSS, as of 12 Nov 2026; CVE List, as of 12 Nov 2026. About the data.

Description

Krb5: mit krb5 kdc unauthenticated cpu dos via quadratic asn.1 sequence of decoding

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.

Source: CVE List, as of 12 Nov 2026. About the data.

What to do

Advisories and patches

No patch, vendor advisory or mitigation is listed in the CVE record. Check Red Hat's own security advisories for a fix, and compare your version with the affected versions below.

Workaround (from the CVE record)

Restrict incoming TCP traffic on port 88 to trusted internal networks or authorized administrative hosts using firewalld. 1. Add a rich rule permitting TCP port 88 only from trusted networks (substitute with the appropriate network CIDR): firewall-cmd --permanent --add-rich-rule='rule family="ipv4" source address="192.168.1.0/24" port port="88" protocol="tcp" accept' 2. Ensure unauthenticated or public access to port 88/tcp is removed: firewall-cmd --permanent --remove-port=88/tcp 3. Apply the changes: firewall-cmd --reload Warning: Applying firewall changes requires reloading firewalld, which may temporarily disrupt network traffic. Restricting TCP access will prevent clients outside the allowed network range from falling back to TCP for large Kerberos ticket exchanges.

This summary is based on the CVE record as of 12 Nov 2026. Check the vendor's advisory before you act: affected versions and fixes can change.