SB2025040919 - Multiple vulnerabilities in Microsoft Windows Local Security Authority (LSA)

Description

This security bulletin contains information about 2 vulnerabilities.

1) Time-of-check Time-of-use (TOCTOU) Race Condition (CVE-ID: CVE-2025-21191)

CWE-ID: CWE-367 - Time-of-check Time-of-use (TOCTOU) Race Condition

CVSSv4: CVSS:4.0/AV:L/AC:L/AT:P/PR:L/UI:N/VC:H/VI:H/VA:H/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 a time-of-check, time-of-use (TOCTOU) race condition in Windows Local Security Authority (LSA). A local user can gain elevated privileges on the target system.

2) Heap-based buffer overflow (CVE-ID: CVE-2025-27478)

CWE-ID: CWE-122 - Heap-based Buffer Overflow

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

The vulnerability allows a local user to execute arbitrary code on the target system.

The vulnerability exists due to a boundary error in Windows Local Security Authority (LSA). A local user can pass specially crafted data to the application, trigger a heap-based buffer overflow and execute arbitrary code on the target system with elevated privileges.

Remediation

Install update from vendor's website.

References

• https://msrc.microsoft.com/update-guide/vulnerability/CVE-2025-21191
• https://msrc.microsoft.com/update-guide/vulnerability/CVE-2025-27478