How severe is CVE-2021-30481?

CVE-2021-30481 has a CVSS 3.x base score of 8.0, rated high severity. It is exploitable over network with high attack complexity, requires low privileges and user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2021-30481 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 4% (88th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-30481?

CVE-2021-30481 affects Valvesoftware Steam Client. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2021-30481?

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-2021-30481 published?

CVE-2021-30481 was published on 2021-04-10 and last updated on 2026-06-17.

CVE-2021-30481

CVE-2021-30481 is a high-severity vulnerability in Valvesoftware Steam Client with a CVSS 3.x base score of 8.0. 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-120.

Key facts

Severity: High (CVSS 3.x base score 8.0)
CVSS v2: 6.0
EPSS exploit prediction: 4% (88th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-120
Affected product: Valvesoftware Steam Client
Published: 2021-04-10
Last modified: 2026-06-17

Description

Valve Steam before 2021-04-17, when a Source engine game is installed, allows remote authenticated users to execute arbitrary code because of a buffer overflow that occurs for a Steam invite after one click.

Frequently asked questions

What is CVE-2021-30481?: Valve Steam before 2021-04-17, when a Source engine game is installed, allows remote authenticated users to execute arbitrary code because of a buffer overflow that occurs for a Steam invite after one click.
How severe is CVE-2021-30481?: CVE-2021-30481 has a CVSS 3.x base score of 8.0, rated high severity. It is exploitable over network with high attack complexity, requires low privileges and user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2021-30481 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 4% (88th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-30481?: CVE-2021-30481 affects Valvesoftware Steam Client. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2021-30481?: 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-2021-30481 published?: CVE-2021-30481 was published on 2021-04-10 and last updated on 2026-06-17.

References

Affected products (1)

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

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