{
  "affected": [
    {
      "database_specific": {
        "unresolved_ranges": [
          {
            "events": [
              {
                "introduced": "0"
              },
              {
                "fixed": "1.4.2"
              }
            ]
          }
        ]
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "b9541505af68ac7b7c093206ac7b1ba88957a5a6"
            }
          ],
          "repo": "https://github.com/geysermc/geyser",
          "type": "GIT"
        },
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "b9541505af68ac7b7c093206ac7b1ba88957a5a6"
            }
          ],
          "repo": "https://github.com/geysermc/geyser",
          "type": "GIT"
        }
      ]
    }
  ],
  "details": "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.",
  "id": "CVE-2021-39177",
  "modified": "2026-03-13T21:53:43.358666731Z",
  "published": "2021-08-30T23:15:07.070Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://updates.playhive.com/weekend-maintenance-disclosure-2kJMaY"
    },
    {
      "type": "FIX",
      "url": "https://github.com/GeyserMC/Geyser/commit/b9541505af68ac7b7c093206ac7b1ba88957a5a6"
    },
    {
      "type": "FIX",
      "url": "https://github.com/GeyserMC/Geyser/security/advisories/GHSA-h77f-xxx7-4858"
    }
  ],
  "related": [
    "GHSA-h77f-xxx7-4858"
  ],
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ]
}