CVE-2026-83910: Critical RPC Runtime OOB Write Lets Attackers Execute Code Remotely

Microsoft has published an advisory for a critical vulnerability in its RPC Runtime Library that allows for remote code execution. The flaw, identified as CVE-2026-83910, enables an unauthorized attacker to execute code over a network by exploiting an out-of-bounds write error. This issue poses a significant risk to systems where the component is exposed to untrusted network traffic.

The vulnerability is classified as critical with a CVSS score of 9.8 according to the National Vulnerability Database. The underlying weakness is categorized under CWE-787, which relates to out-of-bounds write errors in software memory management. The Microsoft Security Update Guide confirms the remote code execution capability via this out-of-bounds write.

Technical Details and Severity

The Microsoft Security Update Guide describes the issue as an out-of-bounds write in the RPC Runtime. This type of memory corruption can allow attackers to overwrite critical data structures or inject malicious code. The advisory confirms that an unauthorized attacker can leverage this flaw to execute code remotely over a network connection.

The National Vulnerability Database record aligns with Microsoft’s description, confirming the remote code execution capability. The CVSS 9.8 rating places this vulnerability among the most severe software flaws reported. Security professionals should treat this issue with high urgency due to the potential for widespread compromise.

Affected Systems and Scope

The vulnerability affects systems running the Microsoft RPC Runtime Library component. The official advisory does not specify particular Windows versions or server editions in the provided summary, but the RPC Runtime is a core component in many Microsoft operating systems. Any system with this library exposed to network traffic is potentially at risk.

The lack of specific version details in the initial summary means the exact scope of affected software versions is not defined in the source material. Organizations must verify which versions of the RPC Runtime are deployed in their environments. The remote nature of the exploit means that external attackers can target these systems without needing local access.

What should you do?

Security teams should immediately inventory their networks to identify systems running the Microsoft RPC Runtime. Since the vulnerability allows remote code execution, reducing the attack surface is the immediate priority. Administrators should check Microsoft’s update guide for the latest patch status and apply fixes as soon as they become available.

What to do and how to stay safe: Microsoft

• Scan your network inventory to identify all systems running the Microsoft RPC Runtime Library to determine exposure.
• Review firewall rules and network segmentation policies to restrict unnecessary inbound traffic to systems hosting RPC services.
• Monitor network logs for unusual outbound connections or unexpected process executions that may indicate exploitation attempts.
• Await official vendor patches and apply them promptly once the vendor provides an update for CVE-2026-83910.

Step-by-step guide: Risk-Based Vulnerability Management: Prioritize Fixes by Actual Danger

General security guidance from the Threat Times newsroom. It is not confirmed advice from the organisations named in this story.

Frequently asked questions

What is the CVE ID for this Microsoft RPC vulnerability?

The vulnerability is identified as CVE-2026-83910.

How severe is this vulnerability rated?

It is rated critical with a CVSS score of 9.8.

What can an attacker do by exploiting this flaw?

An unauthorized attacker can execute code over a network.