CVE-2021-39177

User impersonation due to incorrect handling of the login JWT

CVSS 7.4 HIGHEPSS 1.4%CWE-287

Geyser is a bridge between Minecraft: Bedrock Edition and Minecraft: Java Edition. Versions of Geyser prior to 1.4.2-SNAPSHOT allow anyone that can connect to the server to forge a LoginPacket with manipulated JWT token allowing impersonation as any user. Version 1.4.2-SNAPSHOT contains a patch for the issue. There are no known workarounds aside from upgrading.

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N

Affected products

GeyserMC · Geyser

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References

https://github.com/GeyserMC/Geyser/commit/b9541505af68ac7b7c093206ac7b1ba88957a5a6 https://github.com/GeyserMC/Geyser/security/advisories/GHSA-h77f-xxx7-4858 https://updates.playhive.com/weekend-maintenance-disclosure-2kJMaY