CVE-2020-27837

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.

Published: 2020-12-28 Last update: 2026-06-16 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2020-27837 is rated Low Risk (30.3/100): CVSS Medium severity, with low exploitation likelihood (EPSS 0.22%). Monitor for updates and reassess as exploit intelligence or EPSS changes.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2020-27837

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-06-15 0.04% 0.22% +0.18%
2 2026-01-15 0.06% 0.04% -0.01%
3 2025-11-21 — 0.06% —

Full EPSS history (13 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2020-27837

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
6.4 3.1 MEDIUM
CVSS:3.1/AV:P/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H Click to expand
Attack vector (AV:P)
Hands-on access—USB, keyboard, opening the case—not something you do purely over the wire.
Attack complexity (AC:H)
Even with access, the exploit needs extra luck, timing, or a fussy environment to actually work.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 0.5 5.9 [email protected]
4.4 2.0 MEDIUM
AV:L/AC:M/Au:N/C:P/I:P/A:P Click to expand
Access vector (AV:L)
Requires local access to the target system.
Access complexity (AC:M)
Exploitation needs some favorable conditions, but not exceptional ones.
Authentication (AU:N)
No authentication is required.
Confidentiality impact (C:P)
Partial confidentiality impact.
Integrity impact (I:P)
Partial integrity impact.
Availability impact (A:P)
Partial availability impact.
 3.4 6.4 [email protected]

Weakness enumeration for CVE-2020-27837

OS Trackers for CVE-2020-27837

vendor priority summary link
debian not yet assigned CVE-2020-27837 not yet assigned priority: Debian including 1 source packages (gdm3), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 5. https://security-tracker.debian.org/tracker/CVE-2020-27837
redhat low — https://access.redhat.com/security/cve/CVE-2020-27837
suse low CVE-2020-27837 severity low: SUSE including 57 source package names (gdm, gdm-41.0-1.1, …), 223 product×package rows across 37 product lines (HPE Helion OpenStack 8, SUSE Linux Enterprise High Performance Computing 12 SP5, … (37 product lines)): Known Not Affected 169, Fixed 54. https://www.suse.com/security/cve/CVE-2020-27837/
ubuntu low CVE-2020-27837 low priority: Ubuntu including 1 source packages (gdm3), 16 status rows across 16 suites (bionic, focal, groovy, hirsute, impish, jammy, kinetic, lunar, mantic, noble, oracular, plucky, questing, trusty, upstream, xenial): not-affected 8, ignored 4, needed 2, DNE 1, released 1. https://ubuntu.com/security/CVE-2020-27837

Affected software / configurations for CVE-2020-27837

Vendor Product Version Raw CPE
gnome gnome_display_manager < 3.38.2.1 cpe:2.3:a:gnome:gnome_display_manager:*:*:*:*:*:*:*:*

References for CVE-2020-27837

URL Tags
https://bugzilla.redhat.com/show_bug.cgi?id=1906812 Issue Tracking Patch Third Party Advisory
cvelogic Threat Intelligence