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Actively exploited in the wild. This CVE is on the CISA Known Exploited Vulnerabilities list — treat remediation as urgent. Federal remediation due by 15 Jun 2022.
.net FrameworkApplication · Microsoft

CVE-2015-1671

HIGH · 7.8 CVSS v3.1 Published 2015-05-13
Patch available
A vendor patch is available. No clean upgrade release — apply the published patch.
See remediation →
97/100
Remediation priority · Urgent
In the wild High EPSS No privileges Patch available

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
The Windows DirectWrite library, as used in Microsoft .NET Framework 3.0 SP2, 3.5, 3.5.1, 4, 4.5, 4.5.1, and 4.5.2; Office 2007 SP3 and 2010 SP2; Live Meeting 2007 Console; Lync 2010; Lync 2010 Attendee; Lync 2013 SP1; Lync Basic 2013 SP1; Silverlight 5 before 5.1.40416.00; and Silverlight 5 Developer Runtime before 5.1.40416.00, allows remote attackers to execute arbitrary code via a crafted TrueType font, aka "TrueType Font Parsing Vulnerability."

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

This is a remote code execution vulnerability in Windows DirectWrite library's TrueType font parsing functionality. The flaw allows attackers to execute arbitrary code by tricking users into loading a specially crafted TrueType font file through affected applications including .NET Framework, Office, Lync, and Silverlight.

MitigationApply Microsoft security updates for all affected products, upgrade Silverlight to version 5.1.40416.00 or later, and consider implementing application whitelering or font file restrictions in enterprise environments to block untrusted font loading.

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
.net FrameworkApplication
Affected:= 3.0= 4.0= 4.5= 4.5.1= 4.5.2= 3.5.1= 3.5
Live MeetingApplication
Affected:= 2007
LyncApplication
Affected:= 2010= 2013
SilverlightApplication
Affected:= 5.0

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
Local
Complexity
Low
Privileges
None
User interaction
Required
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/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 installed .NET Framework version
    Open Registry Editor and navigate to HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\NET Framework Setup\NDP\v\Full (or use 'reg query "HKLM\SOFTWARE\Microsoft\NET Framework Setup\NDP\v3.0" /v Version' via command prompt)
    Affected if Version equals 3.0, 3.5, 3.5.1, 4.0, 4.5, 4.5.1, or 4.5.2
  2. Check Microsoft Lync client version
    Open Programs and Features or use 'Get-ItemProperty HKLM:\Software\Microsoft\Windows\CurrentVersion\Uninstall\* | Select DisplayName, DisplayVersion' via PowerShell
    Affected if Lync 2010 or Lync 2013 is installed
  3. Check Microsoft Silverlight version
    Open Control Panel > Programs > Programs and Features, or check 'C:\Program Files\Microsoft Silverlight\version' file, or run 'reg query HKLM\Software\Microsoft\Silverlight /v Version'
    Affected if Silverlight version 5.0 is installed
  4. Check Microsoft Live Meeting 2007
    Open Programs and Features or check Registry under HKLM\Software\Microsoft\Windows\CurrentVersion\Uninstall for entries containing 'Live Meeting'
    Affected if Live Meeting 2007 is installed

If any of the listed .NET Framework versions (3.0, 3.5, 3.5.1, 4.0, 4.5-4.5.2), Lync 2010/2013, Silverlight 5.0, or Live Meeting 2007 are installed and process untrusted TrueType font files, the system is potentially affected.

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.

dbcve · scoped
Patch available Apply the vendor patch
Vendor patch docs.microsoft.com →
Interim mitigation

Apply Microsoft security updates for all affected products, upgrade Silverlight to version 5.1.40416.00 or later, and consider implementing application whitelering or font file restrictions in enterprise environments to block untrusted font loading.

Recommended fix High confidence

Silverlight 5.1.40416.00 or later; .NET Framework receive patches via MS15-080 (Windows Update)

  1. Verify the current version of Silverlight installed by navigating to https://www.microsoft.com/getsilverlight/ or checking Programs and Features
  2. For Silverlight: Uninstall current Silverlight 5.0 and install version 5.1.40416.00 or later from the official Microsoft Silverlight download page
  3. For .NET Framework: Ensure Windows Update is enabled and run Windows Update to receive MS15-080 security update which addresses this vulnerability
  4. For Lync 2010/2013: Apply the relevant security update from MS15-080 via Windows Update or download from Microsoft Update Catalog
  5. For Live Meeting 2007: Apply the security update from MS15-080
  6. For Office 2007/2010: Apply the relevant security update from MS15-080
  7. Restart affected applications and systems after applying updates
  8. Verify the installed version matches the fixed release (Silverlight 5.1.40416.00 or higher)
Caveat This is a security patch update with minimal risk; however, ensure compatibility with existing applications before deploying broadly in production environments

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in .net Framework Exploited in the wild — priority engagement
  • Consultation3.0 h
  • Implementation6.0 h
  • Testing3.0 h
  • Review / QA2.0 h
14.0 hours of engineering $2,490
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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-2015-1671 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