by Kastro
Paper/Archive/CVE-2021-39177

CVE-2021-39177

GeyserMC Geyser — User impersonation due to incorrect handling of the login JWT

EPSS 1%CVSS 9.8
critical.is priorityof 100
44
CVSS 9.8 (NVD)9.8 / 10 × 3029.4Not in CISA KEV+300.0EPSS percentile 73.2.732 × 2014.6No public exploit+100.0SSVC exploitation: unknown+100.0
Description · from the CVE record

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.

Affected

ProductAffectedFixed inSource
Geyser<= 1.4.1-SNAPSHOT–CNA

Scores by source

NVD9.8CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
GitHub_M (CNA)7.4CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N

References

refgithub.com/GeyserMC/Geyser/security/advisories/GHSA-h77f-xxx7-4858refgithub.com/GeyserMC/Geyser/commit/b9541505af68ac7b7c093206ac7b1ba88957a5a6refupdates.playhive.com/weekend-maintenance-disclosure-2kJMaY