High (7.8) in valvesoftware steam client. 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.
Severity
CVSS 3.1
7.8 high
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
EPSS
0.5% chance of exploitation in the next 30 days; higher than 45% of CVEs (scores of 2026-10-31)