Medium severity · published Oct 8, 2026
CVE-2026-107708
MIT krb5 through 1.22.2 KDC NULL Pointer Dereference via S4U2Proxy PAC
4.9
CVSS
0.5%
EPSS
No
On KEV
Description
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.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H
Attack vector
Network
Complexity
Low
Privileges
High
User interaction
None
Confidentiality
None
Integrity
None
Availability
High
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.5% · higher than 44% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
KR
krb5 · MIT
through 1.22.2 · source: vendor
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-107708
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-107708
issue-tracking
https://github.com/krb5/krb5/pull/1510
patch
https://github.com/krb5/krb5/commit/f6e2c397ceda6467ebbaab8ed66d4895c9f1d6a7
patch
https://github.com/krb5/krb5/commit/a88a18cafa1040a0c4f9c8d08288fc98831ec86d
technical-description
https://github.com/krb5/krb5/blob/krb5-1.22.2-final/src/kdc/kdc_util.c#L639-L676
product
https://github.com/krb5/krb5
third-party-advisory
https://www.vulncheck.com/advisories/mit-krb5-through-1.22.2-kdc-null-pointer-dereference-via-s4u2proxy-pac
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