CVE-2025-26669 Overview
CVE-2025-26669 is an out-of-bounds read vulnerability [CWE-125] in the Windows Routing and Remote Access Service (RRAS). An unauthorized remote attacker can exploit this flaw to disclose sensitive information over a network. Exploitation requires user interaction, typically by convincing a victim to connect to or interact with an attacker-controlled resource.
The vulnerability affects a broad range of Windows desktop and server platforms, including Windows 10, Windows 11, and Windows Server versions from 2008 through 2025. Microsoft addressed the issue in the April 2025 security update cycle.
Critical Impact
A successful attack can leak memory contents from a Windows host running RRAS, potentially exposing credentials, configuration data, or other process memory across a network boundary.
Affected Products
- Microsoft Windows 10 (1507, 1607, 1809, 21H2, 22H2)
- Microsoft Windows 11 (22H2, 23H2, 24H2)
- Microsoft Windows Server 2008, 2012, 2016, 2019, 2022, 2022 23H2, and 2025
Discovery Timeline
- 2025-04-08 - CVE-2025-26669 published to NVD
- 2025-07-09 - Last updated in NVD database
Technical Details for CVE-2025-26669
Vulnerability Analysis
The Routing and Remote Access Service is a Windows component that provides routing, VPN, and dial-up connectivity. CVE-2025-26669 is an out-of-bounds read in RRAS message processing. When the service parses an attacker-influenced structure, it reads beyond the bounds of an allocated buffer and returns adjacent memory contents.
The attack is network-reachable and does not require prior authentication. However, the CVSS vector indicates user interaction is required, meaning the victim must initiate a connection, open a crafted file, or click a link that triggers RRAS-handled traffic toward a malicious endpoint. The flaw maps to [CWE-125] Out-of-bounds Read.
Root Cause
The defect stems from missing or insufficient bounds checking on a length or offset field within an RRAS-handled protocol message. The service trusts attacker-supplied size data and reads past the end of the source buffer, exposing uninitialized or adjacent memory.
Attack Vector
An attacker hosts a malicious server or crafts a response that the targeted Windows host processes through RRAS. The victim must perform an action that causes the system to communicate with the attacker-controlled endpoint. The leaked memory is then returned over the network, where it can be reassembled into intelligence used in follow-on attacks.
No verified public proof-of-concept code is available at this time. Refer to the Microsoft CVE-2025-26669 Advisory for vendor technical details.
Detection Methods for CVE-2025-26669
Indicators of Compromise
- Unexpected outbound connections from Windows hosts with the RRAS role enabled to untrusted external endpoints.
- Anomalous RRAS process (svchost.exe hosting RemoteAccess) network activity outside normal VPN or routing patterns.
- Crash, restart, or error events logged for the Routing and Remote Access service following inbound or outbound traffic.
Detection Strategies
- Inventory all systems with the RRAS role installed and correlate with patch status for the April 2025 cumulative update.
- Monitor Windows Event Log channels for RRAS service errors and unusual termination events.
- Apply network IDS signatures to inspect RRAS-related protocol traffic for malformed length fields or oversized structures.
Monitoring Recommendations
- Baseline normal RRAS traffic volume and destinations, alerting on deviations to new external hosts.
- Capture and retain telemetry on user actions that initiate VPN, dial-up, or routing sessions from privileged hosts.
- Track EPSS scoring for CVE-2025-26669, currently at 1.49% with an 81.2 percentile, indicating elevated exploitation likelihood relative to most CVEs.
How to Mitigate CVE-2025-26669
Immediate Actions Required
- Apply the April 2025 Microsoft security updates to all affected Windows 10, Windows 11, and Windows Server systems.
- Audit servers and workstations for the RRAS role and disable it where it is not operationally required.
- Restrict inbound and outbound RRAS traffic to known, trusted endpoints using host and perimeter firewalls.
Patch Information
Microsoft published official guidance and patches in the Microsoft CVE-2025-26669 Advisory. Administrators should deploy the corresponding monthly cumulative update for each affected operating system version.
Workarounds
- Disable the Routing and Remote Access service on hosts that do not require VPN or routing functionality.
- Block RRAS-related ports at the network edge for systems that must remain enabled but only serve internal clients.
- Train users to avoid initiating connections from untrusted links or files that could trigger RRAS communication with attacker-controlled servers.
# Check RRAS service status and disable if not required
Get-Service RemoteAccess
Set-Service -Name RemoteAccess -StartupType Disabled
Stop-Service -Name RemoteAccess
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
