CVE-2021-26423 is classified as a Denial of Service vulnerability affecting multiple Microsoft products, including .NET Core and Visual Studio. With a CVSS score of 7.5, this vulnerability is categorized as high severity, indicating a significant risk to organizations. The vulnerability was published on August 12, 2021, and has since been modified to reflect updated information.
This vulnerability allows attackers to conduct denial of service attacks, potentially bringing down services that rely on the affected software. The urgency for defenders to address this issue cannot be overstated, especially given the risk of service interruptions that could impact business operations.
As of now, there are no known exploits in the wild, but the potential for such attacks remains. Organizations using affected versions of .NET Core and Visual Studio should prioritize patching to mitigate risks associated with this vulnerability.
Organizations should prioritize patching immediately.
Vulnerability Details
.NET Core and Visual Studio Denial of Service Vulnerability is characterized by the ability to cause a service disruption without requiring authentication or user interaction. The CVSS version 3.1 vector indicates that the attack can be executed over a network, with low complexity and no privileges required.
The vulnerability impacts the following products from Microsoft: .NET, .NET Core, PowerShell Core, Visual Studio 2017, and Visual Studio 2019. The CVSS score of 7.5 highlights the potential impact on availability, classified as high, while confidentiality and integrity impacts are noted as none.
The last modification of this vulnerability record was made on November 21, 2024, reflecting ongoing assessments and updates from Microsoft.
Technical Analysis
The root cause of CVE-2021-26423 stems from inadequate handling of service requests within .NET Core and Visual Studio, which can be exploited to induce a denial of service condition. Attackers can leverage this vulnerability over a network, making it accessible from remote locations without the need for user interaction.
The attack complexity is low, allowing easily executed denial of service attacks, which require no privileges or user interaction. The availability impact is categorized as high, indicating that successful exploitation could lead to significant service downtime.
Given the nature of the vulnerability, organizations should ensure robust monitoring and incident response plans are in place to detect and mitigate potential denial of service attacks.
Risk & Impact Analysis
The risk to organizations includes significant service interruptions, which can affect business operations and customer trust. The vulnerability's high CVSS score underscores the urgency for organizations to address this vulnerability within their software environments.
The absence of known exploits does not diminish the potential impact; organizations should remain vigilant and proactive in their defense strategies. The exploitation potential of this vulnerability could lead to a blast radius affecting not only the immediate system but interconnected services reliant on .NET Core and Visual Studio.
Organizations should address in priority patch cycle.
Exploitation Status
Signal | Status |
|---|---|
Known Exploit | No |
Public PoC | No |
Actively Exploited | No |
Ransomware Use | No |
Affected Versions
The affected versions of Microsoft products include .NET Core versions 2.1.0 to 2.1.28, 3.1.0 to 3.1.17, and .NET versions 5.0 to 5.0.8. Additionally, PowerShell Core versions 7.0.0 to 7.0.6 and 7.1.0 to 7.1.3, as well as Visual Studio 2017 versions 15.0 to 15.9, and Visual Studio 2019 versions 16.0 to 16.10 are also impacted.
Mitigation & Remediation
Organizations should apply the latest patches for the affected Microsoft products. Upgrade to .NET Core 2.1.29 or higher, 3.1.18 or higher, and .NET 5.0.9 or higher. PowerShell Core should be updated to version 7.0.7 or higher for version 7.0 and to version 7.1.4 or higher for version 7.1.
For Visual Studio, ensure you are running at least version 15.9 for Visual Studio 2017 and 16.10 for Visual Studio 2019. Organizations that cannot immediately apply patches should consider implementing network controls to limit exposure to potential denial of service attacks.
For further guidance on securing your applications, organizations can explore application security assessment services.
Detection Guidance
Organizations should monitor logs for unusual spikes in traffic that may indicate denial of service attempts. Behavioral anomalies, such as unexpected service downtime or performance degradation, should also be investigated.
Monitoring network signatures can help identify patterns consistent with denial of service attacks, and any unauthorized changes to system configurations should be promptly reviewed.
AppSecure Threat Intelligence Insight
CVE-2021-26423 represents a significant threat within Microsoft’s product ecosystem, particularly as organizations increasingly rely on .NET technologies for their applications. The vulnerability highlights the need for continuous vigilance and proactive security practices in software development and deployment.
Security teams should learn from this incident to reinforce their response strategies against potential denial of service vulnerabilities. Engaging in regular security assessments and adopting a penetration testing methodology can help in identifying and mitigating similar weaknesses in the future.
Furthermore, organizations should stay informed about evolving threats and trends through threat intelligence resources to better prepare for future vulnerabilities.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
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