CVE-2021-39177

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CVSS 3.1

9.8 critical

EPSS

1%p71

Published

Aug 30, 2021 (Aug 30, 2021)

Modified

Jun 17, 2026

Description

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.

Vendors: geysermc
Products: geyser
Weakness: CWE-287
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

NVD CVE.org GitHub PoCs EPSS (1.4%)

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