CVE-2021-30481
Valve Steam through 2021-04-10, when a Source engine game is installed, allows remote...
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.
Attack profile
How easy it is to exploit
- Attack vector
- Network
- Complexity
- High
- Privileges needed
- Low
- User interaction
- Required
What an attacker can affect
- Confidentiality
- High
- Integrity
- High
- Availability
- High
Exploit likelihood
What each source reports
CVE List Score used
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.
- Record
CVE-2021-30481- CVSS 3.1
- 8.0 High
CVSS:3.1/AC:H/AV:N/A:H/C:H/I:H/PR:L/S:C/UI:R - Updated
- 2026-11-02
EUVDEUVD-2021-17404
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.
- Record
EUVD-2021-17404- CVSS 3.1
- 8.0 High
CVSS:3.1/AC:H/AV:N/A:H/C:H/I:H/PR:L/S:C/UI:R - Updated
- 2026-11-02
GitHub AdvisoriesGHSA-3jx7-82j9-5prx
Valve Steam through 2021-04-10, when a Source engine game is installed, allows remote...
Valve Steam through 2021-04-10, 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.
- Record
GHSA-3jx7-82j9-5prx- CVSS 3.1
- 9.0 Critical
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:H - Weakness
- CWE-120
- Updated
- 2026-11-02
NVD
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.
- Record
CVE-2021-30481- CVSS 3.1
- 8.0 High
CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:C/C:H/I:H/A:H - CVSS 3.1
- 9.0 Critical
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:H - CVSS 2.0
- 6.0 Medium
AV:N/AC:M/Au:S/C:P/I:P/A:P - Weakness
- CWE-120
- Updated
- 2026-11-02
Affected products
Public exploits
Links only. Every CVE stores no exploit code.
| Source | Link | Date |
|---|---|---|
| PoC in GitHub | floesen/CVE-2021-30481 | 2021-04-17 |
History
| Recorded | Changed | Sources |
|---|---|---|
| first indexed | CVE List, EUVD, GitHub Advisories, NVD, PoC in GitHub |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2021-30481 is a high vulnerability (CVSS 8.0) in Valvesoftware Steam Client, published April 10, 2021. Public exploit code exists. EPSS puts the chance of exploitation in the next 30 days at 3.53%, the 89th percentile. No source names a fixed version.