GHSA-g588-cjg3-6g78 Steamworks game clients/servers using P2P authentication vulnerable to denial of service

Not scored Published

A malicious game client can cause a denial of service in Steamworks game clients or servers by sending a specific authentication ticket that triggers a panic.

Exploited in the wild
Not known
Login needed
Not needed
Attackable
Over the internet
Victim action needed
Not needed
Fix
Available

What is GHSA-g588-cjg3-6g78?

GHSA-g588-cjg3-6g78 is a denial of service vulnerability in steamworks, published on 5 May 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

Official description

Processing the raw ValidateAuthTicketResponse_t callback data panics when the m_eAuthSessionResponse field is k_EAuthSessionResponseAuthTicketNetworkIdentityFailure. This can lead to denial of service in game clients and servers using the begin_authentication_session API to authenticate players if a malicious game client sends an authentication ticket with a network identity that does not match that of the verifier.

Which versions are affected by GHSA-g588-cjg3-6g78?

3 open source packages ship an affected version, including steamworks.

PackageAffectedFixed in
steamworks crates.ioAll versions0.13.1
steamworks crates.ioAll versions0.13.1
steamworks crates.ioFrom 0.0.0-00.13.1

How do I fix GHSA-g588-cjg3-6g78?

Upgrade steamworks to 0.13.1 or later.

Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.

Is GHSA-g588-cjg3-6g78 being exploited?

There is no known exploitation of GHSA-g588-cjg3-6g78 in the wild and no public exploit code.

Sources

Also known as RUSTSEC-2026-0121.

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