How severe is CVE-2020-15530?

CVE-2020-15530 has a CVSS 3.x base score of 7.8, rated high severity. It is exploitable over local access with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2020-15530 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (41st percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2020-15530?

CVE-2020-15530 affects Valvesoftware Steam Client. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2020-15530?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

When was CVE-2020-15530 published?

CVE-2020-15530 was published on 2020-07-05 and last updated on 2026-06-17.

CVE-2020-15530

CVE-2020-15530 is a high-severity vulnerability in Valvesoftware Steam Client with a CVSS 3.x base score of 7.8. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-362.

Key facts

Severity: High (CVSS 3.x base score 7.8)
CVSS v2: 7.2
EPSS exploit prediction: 1% (41st percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-362
Affected product: Valvesoftware Steam Client
Published: 2020-07-05
Last modified: 2026-06-17

Description

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.

Frequently asked questions

What is CVE-2020-15530?: 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.
How severe is CVE-2020-15530?: CVE-2020-15530 has a CVSS 3.x base score of 7.8, rated high severity. It is exploitable over local access with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2020-15530 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (41st percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2020-15530?: CVE-2020-15530 affects Valvesoftware Steam Client. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2020-15530?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
When was CVE-2020-15530 published?: CVE-2020-15530 was published on 2020-07-05 and last updated on 2026-06-17.

References

http://daniels-it-blog.blogspot.com/2020/07/steam-arbitrary-code-execution-part-2.html

Affected products (1)

cpe:2.3:a:valvesoftware:steam_client:2.10.91.91:*:*:*:*:*:*:*

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