dbcve.org
.net FrameworkApplication · Microsoft

CVE-2013-3171

HIGH · 9.3 CVSS v2.0 Published 2013-07-10
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
100/100
Remediation priority · Urgent
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
The serialization functionality in Microsoft .NET Framework 2.0 SP2, 3.5, 3.5 SP1, 3.5.1, 4, and 4.5 does not properly check the permissions of delegate objects, which allows remote attackers to execute arbitrary code via (1) a crafted XAML browser application (XBAP) or (2) a crafted .NET Framework application that leverages a partial-trust relationship, aka "Delegate Serialization 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

The vulnerability exists in Microsoft .NET Framework's serialization mechanism which fails to properly validate permissions on delegate objects during serialization/deserialization. This allows attackers to execute arbitrary code through malicious XBAP (XAML Browser Applications) or .NET applications operating in partial-trust scenarios by leveraging the unchecked delegate serialization path.

MitigationApply Microsoft security patches for this vulnerability across all affected .NET Framework installations. Additionally, consider disabling XBAP support in browsers and reviewing partial-trust code execution policies until patches can be deployed.

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:= 2.0= 3.5= 3.5.1= 4.0= 4.5

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
M
Authentication
None
Confidentiality
Complete
Integrity
Complete
Availability
Complete

AV:N/AC:M/Au:N/C:C/I:C/A:C

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. Identify installed .NET Framework version
    Run 'reg query "HKLM\SOFTWARE\Microsoft\NET Framework Setup\NDP\v4\Full" /v Version' for .NET 4.x, or 'reg query "HKLM\SOFTWARE\Microsoft\NET Framework Setup\NDP\v2.0.50727" /v Version' for .NET 2.0/3.5 in Command Prompt with admin rights
    Affected if The version returned matches 2.0, 3.5, 3.5.1, 4.0, or 4.5 exactly (note: multiple versions may coexist)
  2. Enumerate all .NET Framework installations
    Run 'reg query "HKLM\SOFTWARE\Microsoft\NET Framework Setup\NDP" /s /v Version | findstr /i "Version"' to list all installed .NET versions on the system
    Affected if Any installed version is 2.0, 3.5, 3.5.1, 4.0, or 4.5
  3. Check if XBAP support is enabled in Internet Explorer
    Open Internet Explorer, go to Internet Options > Security > Custom Level, scroll to 'XAML Browser Applications' and verify if the setting is 'Enabled' or 'Prompt'
    Affected if XBAP support is set to Enabled or Prompt (this enables the browser-based attack vector)
  4. Verify .NET Code Access Security (CAS) policy configuration
    Run 'caspol -m' or check registry key 'HKLM\Software\Microsoft\NET Framework\Policy\APPCAS' to see if partial-trust execution is permitted
    Affected if CAS policies allow partial-trust code execution from remote or untrusted sources

A system is affected if it runs any .NET Framework version 2.0, 3.5, 3.5.1, 4.0, or 4.5 AND has XBAP browser support enabled OR allows partial-trust code execution scenarios.

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
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Apply Microsoft security patches for this vulnerability across all affected .NET Framework installations. Additionally, consider disabling XBAP support in browsers and reviewing partial-trust code execution policies until patches can be deployed.

Recommended fix High confidence

Upgrade to .NET Framework 4.5.2 or later (which includes the fix for this vulnerability)

  1. Install KB2804576 for .NET Framework 4.0
  2. Install KB2840628 for .NET Framework 3.5 SP1 and 3.5.1
  3. Install KB2804577 for .NET Framework 2.0 SP2
  4. Alternatively, upgrade to a later .NET Framework version (4.5.2 or later) that includes the security fix
  5. Apply the update through Windows Update or download from Microsoft Update Catalog
Caveat The patch updates security behavior; ensure your application does not rely on unsafe delegate serialization in partial-trust scenarios

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

Fix this in .net Framework Scoped from the published advisory
  • Consultation6.0 h
  • Implementation12.0 h
  • Testing8.0 h
  • Review / QA4.0 h
30.0 hours of engineering $5,280
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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-2013-3171 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