GitHub Advisoryadvisory · Maven

GHSA-h77f-xxx7-4858 User impersonation due to incorrect handling of the login JWT

HIGH Published 2021-09-07 Modified 2026-10-01 Official page ↗
Aliases
CVE-2021-39177
Ecosystem
Maven
Packages
org.geysermc:connector
Severity
High
CVSS vector
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N
Weaknesses
CWE-287
Reviewed
2021-09-07

Affected packages

• Maven org.geysermc:connector: < 1.4.2-SNAPSHOT → fixed in 1.4.2-SNAPSHOT

Description

Impact This allows anyone that can connect to the server to forge a LoginPacket with manipulated JWT token allowing impersonation as any Bedrock user. Unless credentials are saved in your configuration, online mode is not affected as users are still required to log in separately. If your credentials are saved, there is no risk of exposing your email or password. Patches This was patched as part of https://github.com/GeyserMC/Geyser/commit/b9541505af68ac7b7c093206ac7b1ba88957a5a6 and https://github.com/GeyserMC/Geyser/commit/ab2f5b326fe590e09167e8b45b4b165ac06ecd13. if your Geyser version is `1.4.2-SNAPSHOT` or later, the issue has been addressed on your build. Workarounds Geyser strongly recommends updating to fix this issue. If this isn't possible: • Use online mode and don't save credentials in your Geyser configuration • Use an additional authentication method on the Java server References This was disclosed to us by a staff member over at Hive; you can read their disclosure here: https://updates.playhive.com/changelog/weekend-maintenance-breakdown For more information If you have any questions or comments about this advisory: • Come talk to us over on our Discord server in the #development channel

Related

Alias · CVE (1)

  • CVE-2021-39177 Geyser is a bridge between Minecraft: Bedrock Edition and Minecraft: Java Edition. vulnerability

Weakness · CWE (1)

  • CWE-287 Improper Authentication weakness

References