Buffer overflow in Valvesoftware Steam Client

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.

Vulnerability class: Buffer Overflow

EPSS: 0.035 (88.0th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 8.0 (High). Vector: CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:C/C:H/I:H/A:H.

Affected products

Weakness classification (CWE)

Public proof-of-concept exploits

References

Frequently asked questions

What is CVE-2021-30481?
CVE-2021-30481 is a high-severity vulnerability in Valvesoftware Steam Client, classified under Buffer Copy without Checking Size of Input (Classic Buffer Overflow). CVSS score: 8.0/10. Published 2021-04-10.
How severe is CVE-2021-30481?
High severity. CVSS v3 base score is 8.0 out of 10.
Is CVE-2021-30481 known to be exploited?
13 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.