Steam Platform Vulnerabilities Enable Zero-Click Code Execution

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Steam Platform Vulnerabilities Enable Zero-Click Code Execution

First seen 29 Oct 2026, 17:15 UTC • •54.1

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ThreatCluster •October 29, 2026 at 18:14 UTC

•Steam vulnerabilities allow zero-click remote code execution between logged-in PCs.
•Two stack buffer overflows and an information leak were identified in the research.
•All vulnerabilities reported to Valve are either patched or past the disclosure timeline.

Research by Atredis Partners revealed that Valve's Steam platform had vulnerabilities allowing zero-click remote code execution between computers logged into the same account. The flaws were detailed in a report by researcher Bryan Alexander, which was presented at BSides PDX 2026. The vulnerabilities stemmed from the synchronization of messages between Steam clients, enabling an attacker with access to a logged-in client to execute code without user interaction. Two stack buffer overflows were identified, one in download-schedule notifications and another in application-status updates. Additionally, an information leak was found in outgoing messages. All issues have been reported to Valve through their HackerOne program and are either patched or past the disclosure timeline. However, the report does not specify the fix status for each vulnerability.

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Timeline

2026-10-28

Atredis report published

Atredis Partners released a report detailing vulnerabilities in Steam that allow zero-click remote code execution.

2026-10-28

Presentation at BSides PDX 2026

Bryan Alexander presented findings on Steam vulnerabilities at the BSides PDX 2026 conference.

2026-10-29

Cyberinsider coverage published

Cyberinsider reported on the Atredis findings, detailing the nature of the vulnerabilities and their implications.

More articles in this cluster (2)

Threat Graph

8 entities, 6 inferred relationships (STIX 2.1).

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Technique (5)

Privilege Escalation
Remote Code Execution
Zero-day Exploit
T1055 - Process Injection
T1543.003 - Windows Service

Affected Platform (1)

Windows

Tool (2)

Cmd.exe
WinDbg

Relationships

Privilege Escalation targets Windows
Remote Code Execution targets Windows
Zero-day Exploit targets Windows
T1055 - Process Injection targets Windows
T1543.003 - Windows Service targets Windows
Cmd.exe related to WinDbg

Common questions

What specific vulnerabilities were identified?

Atredis identified two stack buffer overflows and an information leak in Steam's synchronization messages.

Are these vulnerabilities actively being exploited?

The articles do not confirm active exploitation, but proof-of-concept code has been released.

What should users do to protect themselves?

Users should ensure their Steam clients are updated to the latest version to mitigate these vulnerabilities.

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