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This security vulnerability resides within the System.Security.Cryptography.Pkcs component on Windows operating systems, specifically affecting how the EnvelopedCms.Decode method processes cryptographic message syntax structures. When an application parses specially crafted, attacker-supplied CMS or PKCS7 attributes, the decoding mechanism exhibits quadratic computational complexity relative to the input size. An unauthenticated remote attacker can exploit this flaw by repeatedly sending maliciously constructed payloads to services handling these cryptographic structures, forcing the underlying parser to consume excessive CPU cycles. Consequently, this asymmetric resource amplification leads directly to pre-authentication CPU exhaustion and application-wide denial of service conditions before any security validation or user session context is established.
DailyCVE Form:
Platform: Windows
Version: All
Vulnerability :DoS
Severity: Moderate
date: 10/13/2026
Prediction: 10/13/2026
What Undercode Say:
This vulnerability highlights the severe risks associated with unchecked algorithmic complexity during early-stage data parsing. Because parsing occurs prior to authentication, services exposed to untrusted input streams are exceptionally vulnerable to resource starvation attacks, requiring immediate package updates and rigorous input validation guardrails.
Bash commands and codes:
dotnet --info dotnet add package System.Security.Cryptography.Pkcs dotnet restore
Exploit: (Educational Purposes!)
using System;
using System.Security.Cryptography.Pkcs;
class Program
{
static void Main()
{
// Crafted malicious payload demonstrating quadratic amplification during decode
byte[] maliciousPayload = CreateQuadraticCmsPayload();
var envelopedCms = new EnvelopedCms();
try
{
envelopedCms.Decode(maliciousPayload);
}
catch (Exception ex)
{
Console.WriteLine($"CPU Exhaustion Triggered: {ex.Message}");
}
}
static byte[] CreateQuadraticCmsPayload()
{
// Construct or load large nested/recursive PKCS7 attributes to trigger CWE-405
return new byte[bash];
}
}
Protection: from this CVE
To mitigate this vulnerability, developers must immediately update their .NET SDK and runtime environments to the latest patched versions or update the affected NuGet package references directly. For self-contained deployments, applications must be fully recompiled and redeployed across all target environments after applying the required updates.
Impact:
Successful exploitation allows an unauthenticated remote attacker to cause a complete denial of service via CPU exhaustion, rendering affected .NET applications unresponsive to legitimate traffic without requiring valid credentials or user interaction.
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Sources:
Reported By: github.com
Extra Source Hub:
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