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.
Published: 2026-11-09
Score: 7.5 High
EPSS: n/a
KEV: No
AI Analysis

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Remediation

Vendor Workaround

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.

Tracking

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Advisories

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History

Mon, 09 Nov 2026 18:45:00 +0000

Type Values Removed Values Added
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.
Title Krb5: mit krb5 kdc unauthenticated cpu dos via quadratic asn.1 sequence of decoding
First Time appeared Redhat
Redhat enterprise Linux
Redhat hummingbird
Redhat rhel Els
Weaknesses CWE-408
CPEs cpe:/a:redhat:enterprise_linux:10
cpe:/a:redhat:enterprise_linux:8
cpe:/a:redhat:enterprise_linux:9
cpe:/a:redhat:hummingbird:1
cpe:/o:redhat:rhel_els:6
cpe:/o:redhat:rhel_els:7
Vendors & Products Redhat
Redhat enterprise Linux
Redhat hummingbird
Redhat rhel Els
References
Metrics cvssV3_1

{'score': 7.5, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H'}


Subscriptions

Redhat Enterprise Linux Hummingbird Rhel Els
cve-icon MITRE

Status: PUBLISHED

Assigner: redhat

Published:

Updated: 2026-11-09T18:43:39.044Z

Reserved: 2026-10-29T13:10:23.375Z

Link: CVE-2026-119079

cve-icon Vulnrichment

No data.

cve-icon NVD

No data.

cve-icon Redhat

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cve-icon OpenCVE Enrichment

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Weaknesses
  • CWE-408

    Incorrect Behavior Order: Early Amplification