Executive brief
A security vulnerability exists in Windows Kerberos, the primary system used for verifying user identities in corporate networks. An attacker who already has basic access to the network could exploit this flaw to gain higher-level administrative privileges. This could allow them to access sensitive data or perform unauthorized actions across the organization's infrastructure.
Technical details
A privilege escalation vulnerability exists in the Windows Kerberos authentication protocol due to a reliance on untrusted inputs in a security decision (CWE-807). An authenticated attacker with low privileges can exploit this over the network by providing specially crafted input that influences security-critical decisions within the Kerberos service. Successful exploitation requires the attacker to overcome high complexity conditions, but it can result in a complete compromise of confidentiality, integrity, and availability. Microsoft has released security updates to address this issue across affected Windows and Windows Server versions.
Affected products
- Microsoft Windows 10 1607, 1809, 21H2, 22H2
- Microsoft Windows 11 22H3, 23H2, 24H2, 25H2
- Microsoft Windows Server 2008 R2 Service Pack 1 All versions
Timeline
- 2026-01-13: disclosed
- 2026-01-13: advisory