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Case File

CVE-2021-39177

HIGH · CVSS 7.4 EPSS 1.43% Public Exploit

Source: NVD + CISA KEV + EPSS (historical backfill) · Published 2021-08-30 · Last synced 2026-08-04

CyberRota Analysis

This is a high severity vulnerability with a CVSS score of 7.4. It affects Java. Public exploit code or proof-of-concept references have been detected in its references.

Public Exploit Signal

A public exploit, PoC, GitHub repository or Metasploit reference was detected for this CVE.

GitHub PoC Links
github.com ↗ github.com ↗

Note: these links are listed for security research and verification purposes only.

CVE
CVE-2021-39177
Severity
HIGH
CVSS
7.4
EPSS
1.43%
Java

Original NVD 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.