CVE-2025-29828: Windows 11 22h2 RCE Vulnerability

CVE-2025-29828 Overview

CVE-2025-29828 is a memory leak vulnerability (CWE-401) in Windows Cryptographic Services that allows an unauthorized attacker to execute code over a network. The flaw stems from a missing release of memory after its effective lifetime within the cryptographic services component, which can be exploited remotely without requiring authentication or user interaction.

This vulnerability affects modern Windows operating systems including Windows 11 and Windows Server 2022/2025, making it a significant concern for enterprise environments that rely on Windows Cryptographic Services for secure communications and data protection.

Critical Impact

Remote code execution vulnerability in Windows Cryptographic Services allows unauthenticated attackers to execute arbitrary code over the network, potentially compromising system integrity and confidentiality.

Affected Products

• Microsoft Windows 11 22H2
• Microsoft Windows 11 23H2
• Microsoft Windows 11 24H2
• Microsoft Windows Server 2022
• Microsoft Windows Server 2022 23H2
• Microsoft Windows Server 2025

Discovery Timeline

• 2025-06-10 - CVE-2025-29828 published to NVD
• 2025-07-10 - Last updated in NVD database

Technical Details for CVE-2025-29828

Vulnerability Analysis

This vulnerability is classified as CWE-401: Missing Release of Memory after Effective Lifetime, commonly known as a memory leak. In the context of Windows Cryptographic Services, memory that should be freed after cryptographic operations complete is not properly released. Over time or through deliberate exploitation, this memory leak can be leveraged to achieve remote code execution.

The attack requires no privileges or user interaction, though the attack complexity is considered high due to the specific conditions needed for successful exploitation. An attacker who successfully exploits this vulnerability could gain the same privileges as the Windows Cryptographic Services process, potentially leading to full system compromise.

Root Cause

The root cause of CVE-2025-29828 lies in improper memory management within Windows Cryptographic Services. When cryptographic operations are performed, memory buffers are allocated to store intermediate results, keys, or other sensitive data. The vulnerability occurs because these memory allocations are not properly deallocated after use. This memory management failure can lead to heap corruption conditions that attackers can exploit to achieve arbitrary code execution.

Attack Vector

The vulnerability can be exploited over the network without requiring authentication. An attacker would need to send specially crafted requests to a system running vulnerable Windows Cryptographic Services. The network-based attack vector means that any service exposing cryptographic functionality over the network could potentially be targeted.

The exploitation mechanism involves triggering specific cryptographic operations that cause memory to be allocated but never freed. By carefully crafting inputs and controlling the timing of requests, an attacker can manipulate the memory state to gain code execution capabilities. While no user interaction is required, the high attack complexity suggests that reliable exploitation may require specific memory layout conditions or race conditions to be met.

Detection Methods for CVE-2025-29828

Indicators of Compromise

• Unusual memory consumption patterns in processes utilizing Windows Cryptographic Services (lsass.exe, cryptsvc.dll)
• Anomalous network traffic targeting cryptographic service endpoints
• Unexpected crashes or restarts of services dependent on Windows Cryptographic Services
• Memory exhaustion events on systems without corresponding legitimate workload increases

Detection Strategies

• Monitor for abnormal memory growth in cryptographic service processes using performance counters
• Implement network intrusion detection rules for malformed cryptographic protocol requests
• Deploy endpoint detection solutions capable of identifying memory corruption exploitation attempts
• Enable Windows Event Log monitoring for Cryptographic Services errors and warnings (Event IDs in the Microsoft-Windows-Crypto-RSA channel)

Monitoring Recommendations

• Establish baseline memory usage for lsass.exe and related cryptographic processes to identify anomalies
• Configure SIEM alerts for repeated cryptographic operation failures from single source IPs
• Monitor for heap spray patterns and unusual memory allocation sequences in protected processes
• Enable SentinelOne's behavioral AI to detect exploitation attempts targeting Windows system services

How to Mitigate CVE-2025-29828

Immediate Actions Required

• Apply Microsoft security updates as soon as they become available from the Microsoft Security Update Guide
• Prioritize patching of internet-facing Windows Server systems and domain controllers
• Review network segmentation to limit exposure of cryptographic services to untrusted networks
• Enable enhanced monitoring on systems that cannot be immediately patched

Patch Information

Microsoft has released security updates to address this vulnerability. Administrators should consult the Microsoft Security Update Guide for CVE-2025-29828 for specific patch versions and deployment guidance. The patches address the memory leak by ensuring proper deallocation of memory buffers after cryptographic operations complete.

Organizations should test patches in a staging environment before widespread deployment, though the severity of this vulnerability warrants expedited patching schedules for production systems.

Workarounds

• Restrict network access to Windows Cryptographic Services where possible using Windows Firewall rules
• Implement network-level filtering to block potentially malicious cryptographic requests from untrusted sources
• Consider enabling Credential Guard and other memory protection features to harden the attack surface
• Monitor cryptographic service memory usage and implement automated service restart procedures as a temporary measure

# Windows Firewall configuration to restrict cryptographic service access
# Run in elevated PowerShell

# Block inbound connections to RPC endpoints from untrusted networks
New-NetFirewallRule -DisplayName "Restrict Crypto Services - Block External" `
    -Direction Inbound `
    -Protocol TCP `
    -LocalPort 135,445,593 `
    -RemoteAddress "0.0.0.0/0" `
    -Action Block `
    -Profile Domain,Private,Public

# Allow trusted internal networks only
New-NetFirewallRule -DisplayName "Restrict Crypto Services - Allow Internal" `
    -Direction Inbound `
    -Protocol TCP `
    -LocalPort 135,445,593 `
    -RemoteAddress "10.0.0.0/8,172.16.0.0/12,192.168.0.0/16" `
    -Action Allow `
    -Profile Domain,Private