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Fencer Vulns
medium 4.9

CVE-2026-107708 json

MIT krb5 through 1.22.2 KDC NULL Pointer Dereference via S4U2Proxy PAC

published 2026-10-08 31 d ago modified 2026-10-14 26 d ago also EUVD-2026-95255

cvss
4.9
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.5%
EPSS 0.5% chance of exploitation in 30 days, percentile 44%
public exploits
0
none known

Summary

MIT krb5 through 1.22.2 contains a NULL pointer dereference vulnerability in the KDC's get_pac_princ_with_realm() that returns success while leaving the client principal NULL on malformed names. A malicious or compromised cross-realm trusted KDC can send an S4U2Proxy request with a PAC carrying a malformed client name to crash krb5kdc and deny authentication.

Patch / fix

  • krb5 hummingbird 1 1.22.2-10.3.hum1
  • libkadm5 hummingbird 1 1.22.2-10.3.hum1
  • krb5-libs hummingbird 1 1.22.2-10.3.hum1
  • krb5-tests hummingbird 1 1.22.2-10.3.hum1
  • krb5-pkinit hummingbird 1 1.22.2-10.3.hum1
  • krb5-server hummingbird 1 1.22.2-10.3.hum1
  • krb5-server-ldap hummingbird 1 1.22.2-10.3.hum1
  • krb5-workstation hummingbird 1 1.22.2-10.3.hum1

red hat advisories RHSA-2026:80481

  • krb5 SLE Micro 5.5 1.20.1-150500.3.26.1

suse advisories SUSE-SU-2026:4906-1

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-107708 updated cvss 4.9

krb5: krb5: Denial of Service via malformed PAC in S4U2Proxy requests

  • Red Hat Enterprise Linux 6 libkadm5, krb5-libs, krb5-server, krb5-server-ldap, krb5-workstation, krb5 1.21.3-11.el10, +1 more
    affected: workaround, no fix planned “Out of support scope”
  • Red Hat Enterprise Linux 8 libkadm5, krb5-libs, krb5-pkinit, krb5-server, krb5-server-ldap, krb5-workstation, +1 more Red Hat Enterprise Linux 9 libkadm5, krb5-libs, krb5-pkinit, krb5-server, krb5-server-ldap, krb5-workstation, +2 more Red Hat Enterprise Linux 10 krb5 1.21.3-11.el10
    affected: workaround, no fix available
  • Red Hat OpenShift AI (RHOAI) rhoai/odh-core-bff-rhel9, rhoai/odh-dashboard-rhel9, rhoai/odh-mod-arch-maas-rhel9, rhoai/odh-mod-arch-automl-rhel9, rhoai/odh-mod-arch-gen-ai-rhel9, rhoai/odh-mod-arch-mlflow-rhel9, +6 more
    under investigation
  • Red Hat Hardened Images krb5 1.22.2-10.3.hum1, libkadm5 1.22.2-10.3.hum1, krb5-libs 1.22.2-10.3.hum1, krb5-tests 1.22.2-10.3.hum1, krb5-pkinit 1.22.2-10.3.hum1, krb5-server 1.22.2-10.3.hum1, +3 more
    fixed: vendor fix RHSA-2026:80481
  • Red Hat Enterprise Linux 7 libkadm5, krb5-libs, krb5-pkinit, krb5-server, krb5-server-ldap, krb5-workstation, +1 more Red Hat OpenShift AI (RHOAI) rhoai/odh-mlflow-rhel9, rhoai/odh-kube-rbac-proxy-rhel9, rhoai/odh-maas-controller-rhel9, rhoai/odh-mlflow-operator-rhel9, rhoai/odh-model-controller-rhel9, rhoai/odh-ogx-k8s-operator-rhel9, +14 more
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
26 d ago

Exploit prediction

0.52% chance of exploitation in the next 30 days, higher than 44% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 4.0 6.9 CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
CNA 3.1 4.9 CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H
CNA 4.0 6.9 CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Affected products

  • MIT krb5

Classification

Weakness

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.