Summary
TShock allows chat while not fully connected, possible ban evasion
This issue was reported to TShock by @ohayo, but was found by the Discord user by the name of sofurry.com. Please note that this user does not own this domain on the internet, just the discord handle.
TShock overrides certain Terraria vanilla systems, including chat, and the connection handling, for its own purposes, like enforcing bans. When clients connect but do not complete the connection handshake (e.g., send message number 6), they can "exist" on the server, occupy a player slot, chat, and receive data from the server despite not being fully connected. Individuals who exploit this will be able to effectively harass the server, observe the server, and utilize server resources even if banned from the server.
For servers that operate with a proxy that strictly enforces the connection handshake/sequence, this is not an issue, but for smaller servers or servers running vanilla TShock this is an issue worth patching for.
PR body supplied by @ohayo (patch writer):
Terraria's standard server by default checks for bans upon the client sending the ConnectRequest packet, however, TShock instead chooses to check if the client connecting is banned upon the Request World Data packet.
A malicious client can easily just not send this packet, and still join the server even while being banned.
Also by not sending Request World Data, the malicious client is still able to receive all packets from the server & even chat.
Other clients will not be notified of their join/leave but will be able to see them on the player list.
Leading to potential chat spam & "spying" on packets of players within the server.
Impact
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
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Frequently Asked Questions
- What is GHSA-F8MX-CWFH-7HR2? GHSA-F8MX-CWFH-7HR2 is a medium-severity security vulnerability in tshock (nuget), affecting versions <= 5.2.1. It is fixed in 5.2.2.
- Which versions of tshock are affected by GHSA-F8MX-CWFH-7HR2? tshock (nuget) versions <= 5.2.1 is affected.
- Is there a fix for GHSA-F8MX-CWFH-7HR2? Yes. GHSA-F8MX-CWFH-7HR2 is fixed in 5.2.2. Upgrade to this version or later.
- Is GHSA-F8MX-CWFH-7HR2 exploitable, and should I be worried? Whether GHSA-F8MX-CWFH-7HR2 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether GHSA-F8MX-CWFH-7HR2 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
- How do I fix GHSA-F8MX-CWFH-7HR2? Upgrade
tshockto 5.2.2 or later.