What is CVE-2019-15316?

CVE-2019-15316 is a high-severity vulnerability in Microsoft Windows, classified under Time-of-check Time-of-use (TOCTOU) Race Condition. CVSS score: 7.0/10. Published 2019-08-21.

How severe is CVE-2019-15316?

High severity. CVSS v3 base score is 7.0 out of 10.

Vulnerability in Microsoft Windows

CVE-2019-15316

Valve Steam Client for Windows through 2019-08-20 has weak folder permissions, leading to privilege escalation (to NT AUTHORITY\SYSTEM) via crafted use of CreateMountPoint.exe and SetOpLock.exe to leverage a TOCTOU race condition.

Vulnerability class: TOCTOU (Time-of-Check to Time-of-Use)

Published 2019-08-21 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 7.0 (High). Vector: CVSS:3.0/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H.

EPSS exploit prediction

EPSS: 0.004 (36.3th percentile), scored 2026-09-29.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 36th percentile — 36.3% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.004 · newest: 0.004 · change: +0.001

Affected products

Weakness classification (CWE)

References

amonitoring.ru/article/onemore_steam_eop_0day/ (Third Party Advisory)
habr.com/ru/company/pm/blog/464367/ (Third Party Advisory)
www.youtube.com/watch (Exploit, Third Party Advisory)
www.youtube.com/watch (Exploit, Third Party Advisory)

Frequently asked questions

What is CVE-2019-15316?: CVE-2019-15316 is a high-severity vulnerability in Microsoft Windows, classified under Time-of-check Time-of-use (TOCTOU) Race Condition. CVSS score: 7.0/10. Published 2019-08-21.
How severe is CVE-2019-15316?: High severity. CVSS v3 base score is 7.0 out of 10.