ubuntu-cve-2020-27837
Vulnerability from osv_ubuntu
Published
2020-12-28 19:15
Modified
2026-04-22 07:39
Summary
Details

A flaw was found in GDM in versions prior to 3.38.2.1. A race condition in the handling of session shutdown makes it possible to bypass the lock screen for a user that has autologin enabled, accessing their session without authentication. This is similar to CVE-2017-12164, but requires more difficult conditions to exploit.

Severity
6.4 (Medium)
CVSS:3.1/AV:P/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
N/A (UNKNOWN)
low
References
To clipboard 

{
  "affected": [
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "gdm3",
            "binary_version": "3.36.3-0ubuntu0.20.04.4"
          },
          {
            "binary_name": "gir1.2-gdm-1.0",
            "binary_version": "3.36.3-0ubuntu0.20.04.4"
          },
          {
            "binary_name": "libgdm1",
            "binary_version": "3.36.3-0ubuntu0.20.04.4"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:20.04:LTS",
        "name": "gdm3",
        "purl": "pkg:deb/ubuntu/gdm3@3.36.3-0ubuntu0.20.04.4?arch=source\u0026distro=focal"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "3.34.1-1ubuntu1",
        "3.36.3-0ubuntu0.20.04.1",
        "3.36.3-0ubuntu0.20.04.2",
        "3.36.3-0ubuntu0.20.04.3",
        "3.36.3-0ubuntu0.20.04.4"
      ]
    },
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "gdm3",
            "binary_version": "42.0-1ubuntu7.22.04.4"
          },
          {
            "binary_name": "gir1.2-gdm-1.0",
            "binary_version": "42.0-1ubuntu7.22.04.4"
          },
          {
            "binary_name": "libgdm1",
            "binary_version": "42.0-1ubuntu7.22.04.4"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:22.04:LTS",
        "name": "gdm3",
        "purl": "pkg:deb/ubuntu/gdm3@42.0-1ubuntu7.22.04.4?arch=source\u0026distro=jammy"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "41~rc-0ubuntu2",
        "41.0-3ubuntu1",
        "41.0-3ubuntu2",
        "41.3-1ubuntu1",
        "41.3-1ubuntu2",
        "41.3-1ubuntu3",
        "42.0-1ubuntu1",
        "42.0-1ubuntu2",
        "42.0-1ubuntu4",
        "42.0-1ubuntu6",
        "42.0-1ubuntu7",
        "42.0-1ubuntu7.22.04.1",
        "42.0-1ubuntu7.22.04.2",
        "42.0-1ubuntu7.22.04.3",
        "42.0-1ubuntu7.22.04.4"
      ]
    }
  ],
  "aliases": [],
  "details": "A flaw was found in GDM in versions prior to 3.38.2.1. A race condition in the handling of session shutdown makes it possible to bypass the lock screen for a user that has autologin enabled, accessing their session without authentication. This is similar to CVE-2017-12164, but requires more difficult conditions to exploit.",
  "id": "UBUNTU-CVE-2020-27837",
  "modified": "2026-04-22T07:39:37Z",
  "published": "2020-12-28T19:15:00Z",
  "references": [
    {
      "type": "REPORT",
      "url": "https://ubuntu.com/security/CVE-2020-27837"
    },
    {
      "type": "REPORT",
      "url": "https://www.cve.org/CVERecord?id=CVE-2020-27837"
    }
  ],
  "related": [],
  "schema_version": "1.7.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:P/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H",
      "type": "CVSS_V3"
    },
    {
      "score": "low",
      "type": "Ubuntu"
    }
  ],
  "upstream": [
    "CVE-2020-27837"
  ]
}



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Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
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  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.


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