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
Published Aug 21, 2019
7.0
HIGHCVSS 3.0
EPSS 0.45%
Description
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.
Affected products
No data.
- ≤ 2019-08-20
No data.
No Red Hat product state for this CVE.
No package ranges for this CVE.
Remediation
No remediation recorded yet.
Metrics
No CVSS v4.0 score for this CVE.
No CVSS v3.1 score for this CVE.
CVSS:3.0/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
AV:L/AC:M/Au:N/C:C/I:C/A:C
This CVE is not in the KEV list.
No CISA SSVC assessment for this CVE yet.
Estimated probability of exploitation in the wild in the next 30 days (FIRST EPSS). As of Oct 2, 2026.
Score over time
2021–2026- EPSS v1
- EPSS v2
- EPSS v3
- EPSS v4
- EPSS v5
Percentile over time
- EPSS v1
- EPSS v2
- EPSS v3
- EPSS v4
- EPSS v5
Table of values (14 key points)
Flat stretches are collapsed; showing up to 120 newest points.
| Date | Score | Percentile | Model |
|---|---|---|---|
| Oct 2, 2026 | 0.45% (0.00446) | 36.51th | v5 (v2026.06.15) |
| Jun 15, 2026 | 0.39% (0.00389) | 30.47th | v5 (v2026.06.15) |
| Mar 17, 2025 | 0.05% (0.00051) | 13.01th | v4 (v2025.03.14) |
| Dec 12, 2024 | 0.11% (0.00115) | 46.72th | v3 (v2023.03.01) |
| Jun 26, 2024 | 0.08% (0.00081) | 34.84th | v3 (v2023.03.01) |
| Mar 7, 2023 | 0.08% (0.00081) | 32.82th | v3 (v2023.03.01) |
| Mar 6, 2023 | 0.95% (0.00950) | 32.28th | v2 (v2022.01.01) |
| Sep 10, 2022 | 0.95% (0.00950) | 30.63th | v2 (v2022.01.01) |
| Apr 1, 2022 | 0.95% (0.00950) | 28.61th | v2 (v2022.01.01) |
| Feb 4, 2022 | 1.67% (0.01669) | 53.27th | v2 (v2022.01.01) |
| Feb 3, 2022 | 35.03% (0.35026) | 97.90th | v1 |
| Jan 6, 2022 | 35.03% (0.35026) | 97.88th | v1 |
| Sep 1, 2021 | 10.73% (0.10726) | 95.25th | v1 |
| Apr 14, 2021 | 10.73% (0.10726) | 0.00th | v1 |
References (4)
- https://amonitoring.ru/article/onemore_steam_eop_0day/ x_refsource_MISCThird Party Advisory
- https://habr.com/ru/company/pm/blog/464367/ x_refsource_MISCThird Party Advisory
- https://www.youtube.com/watch?v=I93aH86BUaE x_refsource_MISCExploitThird Party Advisory
- https://www.youtube.com/watch?v=ZCHrjP0cMew x_refsource_MISCExploitThird Party Advisory
| Link | Providers | Tags |
|---|---|---|
| https://amonitoring.ru/article/onemore_steam_eop_0day/ | x_refsource_MISCThird Party Advisory | |
| https://habr.com/ru/company/pm/blog/464367/ | x_refsource_MISCThird Party Advisory | |
| https://www.youtube.com/watch?v=I93aH86BUaE | x_refsource_MISCExploitThird Party Advisory | |
| https://www.youtube.com/watch?v=ZCHrjP0cMew | x_refsource_MISCExploitThird Party Advisory |
Change history (0)
No recorded changes yet.