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

Status: published. Published: 2026-11-09. Updated: 2026-11-09.

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.

## Remediation

- 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. (source: CNA: redhat)

## Affected products and versions

- Red Hat / Red Hat Enterprise Linux 10 (krb5): Version range not reported. Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 6 (krb5): Version range not reported. Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 7 (krb5): Version range not reported. Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 8 (krb5): Version range not reported. Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 9 (krb5): Version range not reported. Source: CNA: redhat
- Red Hat / Red Hat Hardened Images (krb5): Version range not reported. Source: CNA: redhat

## Severity and prioritization

- CVSS 3.1: 7.5 (high); CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H; source: CNA: redhat

- CISA KEV: No listing in collected sources

- EPSS: Not available

- SSVC: Not available

- Weaknesses: CWE-408

## Exploit evidence

No exploit evidence in collected sources. This is not proof of no exploitation.

## References

- https://access.redhat.com/security/cve/CVE-2026-119079 (CNA: redhat; vdb-entry, x_refsource_REDHAT)

- https://bugzilla.redhat.com/show_bug.cgi?id=2479231 (CNA: redhat; issue-tracking, x_refsource_REDHAT)

## Provenance

- CNA: redhat: https://www.cve.org/CVERecord?id=CVE-2026-119079; retrieved 2026-11-09; source updated 2026-11-09

Revision: 3a524677a83423d038822e34fc8be6f7f9d7128ccc3098cb9749f15c7f3d29aa

Canonical: https://y2.dev/cve/CVE-2026-119079

## Agent and API access

Public CVE pages, Markdown, and JSON are free to read without an account or API key.

- Public catalog: https://y2.dev/cve/index.json. Follow nextCursor with the same search, filters, sort, and limit (1–100). A null cursor marks the end.

- WebMCP: search_cve_disclosures, get_cve_disclosure, get_cve_page_markdown, get_y2_cve_access. Available in compatible browsers.

- Cyber API: https://api.y2.dev/api/v2/cyber/cves and https://api.y2.dev/api/v2/cyber/cves/{cveId}.

- Y2 Pro or Elite: create a workspace API key with the intel:cyber scope and send Authorization: Bearer <Y2_API_KEY>. Setup: https://y2.dev/docs/api/create-key.

- x402: Pay per request without an account or API key. Omit Authorization, read the HTTP 402 PAYMENT-REQUIRED challenge, validate its current requirements, and retry with PAYMENT-SIGNATURE through an authorized payment client. These browser tools never make payments. Guide: https://y2.dev/docs/api/x402.

- OpenAPI: https://y2.dev/api/openapi.yaml. Agent access metadata: https://y2.dev/cve/agent.json.

Collected public records only. Check source status for coverage and freshness.