SB20260113123 - Multiple vulnerabilities in Microsoft Windows Kerberos

Description

This security bulletin contains information about 2 vulnerabilities.

1) Reliance on Untrusted Inputs in a Security Decision (CVE-ID: CVE-2026-20849)

CWE-ID: CWE-807 - Reliance on Untrusted Inputs in a Security Decision

CVSSv4: CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:U/U:Green

The vulnerability allows a remote user to escalate privileges on the system.

The vulnerability exists due to reliance on untrusted input for a security decision in Windows Kerberos, which leads to security restrictions bypass and privilege escalation.

2) Use of a broken or risky cryptographic algorithm (CVE-ID: CVE-2026-20833)

CWE-ID: CWE-327 - Use of a Broken or Risky Cryptographic Algorithm

CVSSv4: CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N/E:U/U:Clear

The vulnerability allows a local user to compromise the target system.

The vulnerability exists due to use of a broken or risky cryptographic algorithm in Windows Kerberos. A local user can gain access to sensitive information on the system.

Remediation

Install update from vendor's website.

References

• https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-20849
• https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-20833