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LightdmApplication · Lightdm Project

CVE-2015-8316

MEDIUM · 5.9 CVSS v3.0 Published 2017-09-06
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
68/100
Remediation priority · Elevated
Remotely reachable No privileges Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
Array index error in LightDM (aka Light Display Manager) 1.14.3, 1.16.x before 1.16.6 when the XDMCP server is enabled allows remote attackers to cause a denial of service (process crash) via an XDMCP request packet with no address.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

Array index error in LightDM versions 1.14.3 and 1.16.x before 1.16.6 allows remote attackers to cause denial of service via crafted XDMCP request packets with no address field. The vulnerability occurs when the XDMCP server is enabled and the code does not properly validate the address before using it as an array index.

MitigationUpgrade LightDM to version 1.16.6 or later, or if upgrade is not possible, disable the XDMCP server if not required.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
LightdmApplication
Affected:= 1.14.3= 1.16= 1.16.1= 1.16.2= 1.16.3= 1.16.4

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
High
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Check if LightDM is installed
    Run `dpkg -l lightdm` on Debian-based systems or `rpm -q lightdm` on RHEL-based systems. Alternatively, check for the binary at `/usr/sbin/lightdm`.
    Affected if LightDM is not installed on the system, this CVE does not apply.
  2. Determine installed LightDM version
    Run `lightdm --version` or check your package manager for the installed version.
    Affected if The installed version is 1.14.3, 1.16, 1.16.1, 1.16.2, 1.16.3, or 1.16.4.
  3. Locate LightDM configuration file
    Check for `/etc/lightdm/lightdm.conf` or `/etc/lightdm/lightdm.conf.d/*.conf`.
    Affected if Configuration file exists on the system.
  4. Verify if XDMCP server is enabled
    Search the LightDM configuration file for `[XDMCP]` section and look for `enabled=true` or similar XDMCP enablement directives. Use `grep -r "XDMCP" /etc/lightdm/` to find XDMCP-related settings.
    Affected if XDMCP is explicitly enabled in the LightDM configuration.

The system is affected only if LightDM version is 1.14.3 or any 1.16.x version through 1.16.4 AND the XDMCP server is enabled in the configuration.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

From vendor data
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Upgrade LightDM to version 1.16.6 or later, or if upgrade is not possible, disable the XDMCP server if not required.

Fix this in Lightdm Scoped from the published advisory
  • Consultation1.0 h
  • Implementation2.0 h
  • Testing2.0 h
  • Review / QA1.0 h
6.0 hours of engineering $1,040
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2015-8316 in production — separate from our analysis above.

No notes yet

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data