External risk intelligence

Microsoft PEAP Remote Code Execution Vulnerability

CVE advisorySeverity: CRITICAL (CVSS 9.8)

CVE-2023-21692

The vulnerability affects the Protected Extensible Authentication Protocol (PEAP) in Windows. While used for network authentication, PEAP is typically employed in internal enterprise environments like Wi-Fi or VPNs. Direct exposure of this authentication protocol to the public internet is uncommon and generally restricted by standard internal network security controls.

Remote Code Execution

Microsoft Windows 10 1507

before 10.0.10240.19747before 10.0.14393.5717before 10.0.17763.4010before 10.0.19042.2604before 10.0.19044.2604before 10.0.19045.2604before 10.0.22000.1574before 10.0.22621.1265r2

Halo Surface Signal: 2 out of 5 — less likely to be public-facing.

External exposure likelihood

Horizon Alert

Summary of the vulnerability and why it matters

This advisory details a critical vulnerability within Microsoft's Protected Extensible Authentication Protocol (PEAP) that could allow remote code execution. The issue affects various Windows operating systems and server versions, potentially impacting network authentication services. The primary concern is confirming if these specific services are exposed externally, as the protocol is typically used in internal network environments.

A flaw exists in Windows network authentication.
Consider impact if external authentication is exposed.
Focus on confirming relevance and external exposure.

Attack Path

How an attacker could exploit the issue

An attacker could remotely target a vulnerable system over the network by exploiting how the Microsoft Protected Extensible Authentication Protocol (PEAP) handles certain data. This could allow an attacker to execute arbitrary code, potentially leading to a full compromise of the affected system. The vulnerability exists within the authentication process itself.

No special access is required.
Attacker triggers vulnerability through PEAP.
Risk of remote code execution.

Live Threat

Current exploitation, exposure, and threat context

This vulnerability could affect the integrity and availability of systems that use the Microsoft Protected Extensible Authentication Protocol (PEAP) for network authentication. When exploited, it may allow an unauthenticated attacker to execute arbitrary code on a vulnerable system.

System integrity and availability.
Remote code execution over the network.
Unauthorized control over affected systems.

Operational Fix

Recommended remediation, mitigation, and detection steps

This critical vulnerability in Microsoft's Protected Extensible Authentication Protocol (PEAP) requires immediate attention from infrastructure and security teams. The first practical step is to identify all Windows endpoints running the affected components, confirm their network exposure and business criticality, and then assign ownership for remediation planning.

Identify and confirm affected systems.
Verify network exposure and criticality.
Plan remediation based on risk.

Supplementary metadata

CVSS vector

Validate whether this threat affects your internet-facing exposure.

Halo Threat Intelligence helps prioritize remediation with Halo Surface Signal and H/A/L/O context. Start exposure validation with a free external attack surface trial.

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Frequently asked questions

What is the software context for CVE-2023-21692?

This critical vulnerability resides within the Microsoft Protected Extensible Authentication Protocol (PEAP), a component integrated into numerous Windows desktop and server operating systems. It is primarily utilized for secure network authentication services, including enterprise Wi-Fi and VPN connections.

How is this vulnerability classified?

The flaw is categorized as CWE-122, identifying it as a heap-based buffer overflow. This indicates a memory management error where the software fails to properly handle data during the authentication sequence, potentially permitting unauthorized code execution.

How can the vulnerability be triggered?

An attacker can initiate the vulnerability remotely over the network by sending malicious data to the PEAP component during the authentication process. No specific user interaction or privileged access is required to attempt to exploit this memory management weakness.

How relevant is this risk to my organization?

According to the Halo Surface Signal, this risk is Unlikely. Because PEAP is typically deployed within protected internal enterprise environments, direct exposure to the public internet is uncommon and usually mitigated by standard internal network security controls.

What are the recommended steps for response?

Infrastructure teams should prioritize identifying all systems running the affected Windows versions. Once identified, evaluate the specific network exposure and business criticality of these assets to develop an informed remediation plan for securing the affected environment.

References

msrc.microsoft.com/update-guide/vulnerability/CVE-2023-21692

Written by Nicholas Merritt

Nicholas Merritt is VP of Security Solutions at Halo Security. With more than 25 years across application security, vulnerability prioritization, and offensive security, he helps teams translate threat data into practical exposure validation and remediation focus. He authors Halo Threat Intelligence CVE advisories using Halo Surface Signal and H/A/L/O context to prioritize internet-facing risk.