CVE-2017-8900

LightDM through 1.22.0, when systemd is used in Ubuntu 16.10 and 17.x, allows physically proximate attackers to bypass intended AppArmor restrictions and visit the home directories of arbitrary users by establishing a guest session.

Published: 2017-05-12 Last update: 2026-06-16 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2017-8900 is rated Low Risk (30.4/100): CVSS Medium severity, with low exploitation likelihood (EPSS 0.42%). 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-2017-8900

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 0.07% 0.42% +0.35%
2 2026-04-05 0.05% 0.07% +0.02%
3 2026-01-01 — 0.05% —

Full EPSS history (5 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2017-8900

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
4.6 3.0 MEDIUM
CVSS:3.0/AV:P/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N 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:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
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:N)
Data isn’t meaningfully altered or forged.
Availability (A:N)
Service keeps running; no real outage angle.
 0.9 3.6 [email protected]
2.1 2.0 LOW
AV:L/AC:L/Au:N/C:P/I:N/A:N Click to expand
Access vector (AV:L)
Requires local access to the target system.
Access complexity (AC:L)
Exploitation conditions are straightforward and predictable.
Authentication (AU:N)
No authentication is required.
Confidentiality impact (C:P)
Partial confidentiality impact.
Integrity impact (I:N)
No integrity impact.
Availability impact (A:N)
No availability impact.
 3.9 2.9 [email protected]

Weakness enumeration for CVE-2017-8900

OS Trackers for CVE-2017-8900

vendor priority summary link
debian unimportant CVE-2017-8900 unimportant priority: Debian including 1 source packages (lightdm), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 5. https://security-tracker.debian.org/tracker/CVE-2017-8900
ubuntu medium CVE-2017-8900 medium priority: Ubuntu including 1 source packages (lightdm), 5 status rows across 5 suites (trusty, upstream, xenial, yakkety, zesty): released 2, DNE 1, needs-triage 1, not-affected 1. https://ubuntu.com/security/CVE-2017-8900

Affected software / configurations for CVE-2017-8900

Vendor Product Version Raw CPE
lightdm_project lightdm <= 1.22.0 cpe:2.3:a:lightdm_project:lightdm:*:*:*:*:*:*:*:*

References for CVE-2017-8900

URL Tags
http://www.securityfocus.com/bid/98554 Third Party Advisory VDB Entry
https://launchpad.net/bugs/1663157 Issue Tracking Patch Vendor Advisory
https://people.canonical.com/~ubuntu-security/cve/2017/CVE-2017-8900.html Patch Vendor Advisory
https://www.ubuntu.com/usn/usn-3285-1/ Patch Vendor Advisory
cvelogic Threat Intelligence