CVE-2020-15530: Valvesoftware Steam Client

High severity, CVSS 7.8. EPSS: 0.5% chance of exploitation in the next 30 days.

An issue was discovered in Valve Steam Client 2.10.91.91. The installer allows local users to gain NT AUTHORITY\SYSTEM privileges because some parts of %PROGRAMFILES(X86)%\Steam and/or %COMMONPROGRAMFILES(X86)%\Steam have weak permissions during a critical time window. An attacker can make this time window arbitrarily long by using opportunistic locks.

Affected products

Published 2020-07-05. Last modified 2026-06-17.