High

TShock Security Escalation Exploit

Disclosed: 18.12.2024
Updated: 11.10.2026 11:23

Impact

An issue with the way OTAPI manages client connections results in stale UUIDs remaining on RemoteClient instances after a player disconnects.

Because of this, if the following conditions are met a player may assume the login state of a previously connected player:

The server has UUID login enabled
An authenticated player disconnects
A subsequent player connects with a modified client that does not send the ClientUUID#68 packet during connection
The server assigns the same RemoteClient object that belonged to the originally authenticated player to the newly connected player

Patches

TShock 5.2.1 hotfixes this issue. A more robust fix will be made to OTAPI itself.

Workarounds

Implement a RemoteClient reset event handler in a plugin like so:

csharp

public override void Initialize()
{
        On.Terraria.RemoteClient.Reset += RemoteClient_Reset;
}

private static void RemoteClient_Reset(On.Terraria.RemoteClient.orig_Reset orig, RemoteClient client)
{
	client.ClientUUID = null;
        orig(client);
}

Affected software

Click a technology to see all vulnerabilities affecting it.

Platform	Package	Vulnerable versions	Fixed in
.NET (NuGet)	TShock	>= 4.3.21, < 5.2.1	5.2.1

References

CVSS score -

CVSS vector: CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:H/VI:H/VA:H/SC:L/SI:H/SA:H
Weakness (CWE): CWE-305, CWE-613, CWE-863
Platform: .NET (NuGet)
Package: TShock
Disclosed: 18.12.2024
Updated: 11.10.2026 11:23

Sources and licenses

OSV / GitHub Advisory Database - GHSA-hvm9-wc8j-mgrc - CC BY 4.0

Vulnerability history: TShock

All published vulnerabilities of this package (.NET (NuGet)), newest first. Shows whether this is a one-off slip or a package that needs watching.

Total entries: 2
First → latest: 12.2024 02.2025
Without a fix: 0
Exploited in attacks: 0

Severity breakdown

High 1
Medium 1

Disclosures per year

2024: 1
2025: 1
2026: 0

03.02.2025

TShock allows chat while not fully connected, possible ban evasion

Medium ghsa-f8mx-cwfh-7hr2 < 5.2.2 5.2.2
18.12.2024

TShock Security Escalation Exploit this entry

High ghsa-hvm9-wc8j-mgrc >= 4.3.21, < 5.2.1 5.2.1

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