CVE-2021-30481

Name: CVE-2021-30481
Creator: NVD / NIST
Published: 2021-04-10T19:15:11.707+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

CRITICALCVSS 9/10EPSS 3.50%

Last modified Jun 17, 2026

CVE-2021-30481 is a critical-severity vulnerability rated 9/10 on the CVSS scale. 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.. EPSS estimates a 3.50% chance of exploitation in the next 30 days.

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.

Metrics

CVSS 3.1

9/10

CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:H

EPSS Probability

3.50%

87.7th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-120

Affected Software

Vendor	Product	Versions
Valvesoftware	Steam Client	<= 2021-04-10

References

https://news.ycombinator.com/item?id=26762170Issue Tracking, Third Party Advisory
https://twitter.com/floesen_/status/1337107178096881666Third Party Advisory
https://twitter.com/the_secret_club/status/1380868759129296900Exploit, Third Party Advisory
https://www.youtube.com/watch?v=rNQn--9xR1QExploit, Third Party Advisory
https://news.ycombinator.com/item?id=26762170Issue Tracking, Third Party Advisory
https://twitter.com/floesen_/status/1337107178096881666Third Party Advisory
https://twitter.com/the_secret_club/status/1380868759129296900Exploit, Third Party Advisory
https://www.youtube.com/watch?v=rNQn--9xR1QExploit, Third Party Advisory

Timeline

Published: Apr 10, 2021
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2021-30481?

How severe is CVE-2021-30481?

CVE-2021-30481 has a CVSS score of 9/10 (CRITICAL severity). The EPSS model estimates a 3.50% probability of exploitation in the next 30 days.

How do I fix CVE-2021-30481?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2021-30481?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST