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.net FrameworkApplication · Microsoft

CVE-2013-3861

HIGH · 7.8 CVSS v2.0 Published 2013-10-09
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
87/100
Remediation priority · High
High EPSS 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
Microsoft .NET Framework 2.0 SP2, 3.5, 3.5 SP1, 3.5.1, 4, and 4.5 allows remote attackers to cause a denial of service (application crash or hang) via crafted character sequences in JSON data, aka "JSON 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 · moderate confidence

This is a denial of service vulnerability in Microsoft .NET Framework versions 2.0 SP2 through 4.5. Remote attackers can exploit it by sending specially crafted character sequences in JSON data to applications that parse JSON, causing the affected application to crash or hang.

MitigationApply the relevant Microsoft security update (MS13-052 or corresponding bulletin) to all affected .NET Framework installations. Validate that JSON parsing functionality continues to work correctly after patching.

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
Low
Authentication
None
Confidentiality
None
Integrity
None
Availability
Complete

AV:N/AC:L/Au:N/C:N/I:N/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
    Open Registry Editor and navigate to HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\NET Framework Setup\NDP\v4\Full (for .NET 4.x) or HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\NET Framework Setup\NDP\v2.0 (for .NET 2.0/3.x). Check the Release or Version value. Alternatively, run 'wmic product list' or check Programs and Features for Microsoft .NET Framework entries.
    Affected if The installed version falls within 2.0 SP2 through 4.5 (any 2.0, 3.5, 3.5.1, 4.0, or 4.5 installation). Compare your version number to the affected range.
  2. Verify presence of JSON parsing assemblies
    Check for the presence of System.Web.Extensions.dll (for ASP.NET AJAX JSON) or System.Runtime.Serialization.Json.dll in the .NET Framework assembly folders, typically located at C:\Windows\Microsoft.NET\Framework\v2.0.50727 or C:\Windows\Microsoft.NET\Framework\v4.0.30319.
    Affected if These JSON-related assemblies exist on the system, indicating JSON parsing capability is available.
  3. Identify applications using JSON parsing
    Search application directories and web roots for web.config files containing System.Web.Extensions or System.Runtime.Serialization.Json references. Check for .dll files that reference JSON serialization (look for DataContractJsonSerializer or JavaScriptSerializer usage in bin folders).
    Affected if Applications or services are found that utilize JSON parsing libraries from the affected .NET Framework versions.
  4. Check for publicly exposed JSON endpoints
    Review IIS configuration (applicationHost.config) and individual web.config files for web services or APIs that accept JSON input (check for content-type: application/json handlers or WebInvoke methods with RequestFormat = WebMessageFormat.Json).
    Affected if Web applications or WCF services are configured to accept JSON requests from network clients.

A system is affected if it runs any .NET Framework version between 2.0 SP2 and 4.5 and has applications or services that parse JSON data from external sources.

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

Apply the relevant Microsoft security update (MS13-052 or corresponding bulletin) to all affected .NET Framework installations. Validate that JSON parsing functionality continues to work correctly after patching.

Fix this in .net Framework Scoped from the published advisory
  • Consultation3.0 h
  • Implementation6.0 h
  • Testing4.0 h
  • Review / QA2.0 h
15.0 hours of engineering $2,640
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Scan for this in your stack

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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-2013-3861 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
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