CVE-2026-107708
MIT krb5 through 1.22.2 KDC NULL Pointer Dereference via S4U2Proxy PAC
- State
- Published
- Severity
- 6.9 Medium
- Published
- Oct 8, 2026
- Updated
- Oct 14, 2026
- Reserved
- Oct 8, 2026
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.
Scores
| CVSS | Score | Vector | Source |
|---|---|---|---|
| 4.0 | 6.9 Medium | 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 | VulnCheck |
| 3.1 | 4.9 Medium | CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H | VulnCheck |
Weaknesses
- CWE-476 NULL Pointer Dereference
Affected Products
| Product | Versions |
|---|---|
krb5MIT |
|
References
- Pull Request #1510issue-trackingpatch
- Patch Commitpatch
- https://github.com/krb5/krb5/commit/a88a18cafa1040a0c4f9c8d08288fc98831ec86dpatch
- https://github.com/krb5/krb5/blob/krb5-1.22.2-final/src/kdc/kdc_util.c#L639-L676technical-description
- https://github.com/krb5/krb5product
- VulnCheck Advisory: MIT krb5 through 1.22.2 KDC NULL Pointer Dereference via S4U2Proxy PACthird-party-advisory
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