CVE-2021-30481 Memory corruption in n/a

High 8.0 Published 10 Apr 2021 Updated 3 Nov 2025

Remote authenticated users can execute arbitrary code via a buffer overflow in Steam invites when a Source engine game is installed.

Exploited in the wild: Not known
Login needed: Any signed-in user
Attackable: Over the internet
Victim action needed: A user has to click or open something
Fix: None listed

What is CVE-2021-30481?

CVE-2021-30481 is a high-severity memory corruption vulnerability in n/a, published on 10 Apr 2021. Any signed-in user can exploit it over the network, and only if a user opens a file or follows a link.

Official 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.

Weakness: CWE-120

Which versions are affected by CVE-2021-30481?

It affects 1 product.

Products include Valvesoftware Steam Client.

How do I fix CVE-2021-30481?

No fix has been published for CVE-2021-30481 yet. Limit exposure of the affected software until one is available.

Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.

Is CVE-2021-30481 being exploited?

There is no known exploitation of CVE-2021-30481 in the wild and no public exploit code.

Public exploit code: 1 proofs of concept on GitHub.

Sources

Also known as GHSA-3jx7-82j9-5prx.