---
id: CVE-2026-107708
title: >-
  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
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 tru…
severity: medium
cvss: 4.9
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H'
cwe:
  - CWE-476
published: '2026-10-08'
updated: '2026-10-08'
sourceUpdated: '2026-10-08T21:33:42.423'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-107708'
references:
  - url: 'https://github.com/krb5/krb5'
    label: disclosure@vulncheck.com
  - url: >-
      https://github.com/krb5/krb5/blob/krb5-1.22.2-final/src/kdc/kdc_util.c#L639-L676
    label: disclosure@vulncheck.com
  - url: >-
      https://github.com/krb5/krb5/commit/a88a18cafa1040a0c4f9c8d08288fc98831ec86d
    label: disclosure@vulncheck.com
  - url: >-
      https://github.com/krb5/krb5/commit/f6e2c397ceda6467ebbaab8ed66d4895c9f1d6a7
    label: disclosure@vulncheck.com
  - url: 'https://github.com/krb5/krb5/pull/1510'
    label: disclosure@vulncheck.com
  - url: >-
      https://www.vulncheck.com/advisories/mit-krb5-through-1.22.2-kdc-null-pointer-dereference-via-s4u2proxy-pac
    label: disclosure@vulncheck.com
tags:
  - nvd
ingestedAt: '2026-10-08T22:11:53.857Z'
---

## Overview

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.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.