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TI-2020-16907 Aliases CVE-2020-27837GHSA-xpm4-75c2-wrgc

Race condition in gdm

Priority LOW 28CWE-362Published · Updated

Key facts

Attack vector
Physical
Privileges required
None
User interaction
None
Attack complexity
High
Impact type
—
Confidentiality · integrity · availability
High · High · High
Fix status
Partial Red Hat: 2 without a fix

Attack profile from CVSS 3.1 · NVD. Fix status from CNA and Red Hat.

Summary

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.

Why it matters now

EPSS 0.00228 13th percentileScored 2026-11-07
Fix Partial gdm: 3.38.2.1Red Hat: 2 without a fix

SSVC decision points

Not available: CISA has not published SSVC decision points for this record.

Affected products

VendorProductAffected versionsFixed inStatusSource
—gdmbefore 3.38.2.13.38.2.1Patch availableCNA
  • gdm Vendor— Affected before 3.38.2.1 Fixed in 3.38.2.1 Patch available CNA

CPE configurations NVD · 1

CPEVersionsRoleVendor
cpe:2.3:a:gnome:gnome_display_manager:*:*:*:*:*:*:*:*before 3.38.2.1VulnerableGNOME
  • cpe:2.3:a:gnome:gnome_display_manager:*:*:*:*:*:*:*:* Versions before 3.38.2.1 Vulnerable ·GNOME

Remediation

  • Fix · CNA gdm Fixed in 3.38.2.1

Vendor assessments

Red Hat

Red Hat rating: Low. Red Hat's page for this CVE →

ProductStatusPlan or fix
Red Hat Enterprise Linux 6AffectedNo fix planned: Out of support scope
Red Hat Enterprise Linux 7AffectedNo fix planned: Out of support scope
Not affected: 1 product
  • Red Hat Enterprise Linux 8

Timeline

  1. 2026-10-02 Threatist record created from CVE-2020-27837
  2. 2026-10-03 Alias added: GHSA-xpm4-75c2-wrgc

References

Patch 1

  • TI-2018-10342 The daemon in GDM through 3.29.1 does not properly unexport display objects from its… CVSS 3.0HIGH 7.8
  • TI-2020-12684 gdm3 would start gnome-initial-setup if it cannot contact accountservice CVSS 3.1HIGH 7.2
  • TI-2015-06234 GNOME Display Manager (gdm) before 3.18.2 allows physically proximate attackers to bypass… CVSS 2.0HIGH 7.2
  • TI-2013-03642 GNOME Display Manager (gdm) before 2.21.1 allows local users to change permissions of… CVSS 2.0MEDIUM 6.9
  • TI-2019-02837 Improper authentication in Gnome Projectr gdm CVSS 3.0MEDIUM 6.4
  • TI-2017-08954 A flaw was discovered in gdm 3.24.1 where gdm greeter was no longer setting the ran_once… CVSS 3.0MEDIUM 6.4
See all 9 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences