CVE-2025-29811 Overview
CVE-2025-29811 is an elevation of privilege vulnerability in the Windows Mobile Broadband component. The flaw stems from improper input validation ([CWE-20]) and allows an authenticated local attacker to elevate privileges on the affected system. Microsoft disclosed the issue as part of its April 2025 security release and rates it High with a CVSS 3.1 score of 7.8.
Successful exploitation grants an attacker high impact against confidentiality, integrity, and availability. The vulnerability affects current Windows 11 client editions and Windows Server 2022 23H2 and Windows Server 2025.
Critical Impact
An authorized local attacker can elevate privileges to compromise the host running a vulnerable Windows Mobile Broadband stack.
Affected Products
- Microsoft Windows 11 22H2, 23H2, and 24H2
- Microsoft Windows Server 2022 23H2
- Microsoft Windows Server 2025
Discovery Timeline
- 2025-04-08 - CVE-2025-29811 published to NVD by Microsoft
- 2026-06-17 - Last updated in NVD database
Technical Details for CVE-2025-29811
Vulnerability Analysis
The vulnerability resides in the Windows Mobile Broadband component, which manages cellular data connections through Mobile Broadband Interface Model (MBIM) devices and related services. Improper input validation in this component allows a local attacker to submit malformed data that the driver or service processes without adequate boundary or type checks.
Exploitation requires a local, authenticated user context. No user interaction is required, and the attack complexity is low. Windows Mobile Broadband services typically run at elevated privilege levels, so mishandled input crossing this trust boundary can yield SYSTEM-level code execution or equivalent capability.
The issue is classified under [CWE-20] Improper Input Validation. Attackers commonly abuse such flaws to escape sandboxed processes, escalate from a standard user account, or complete post-exploitation objectives after initial access via phishing or malware delivery.
Root Cause
The Mobile Broadband component accepts attacker-controllable input and passes it to privileged code paths without sufficient validation of size, structure, or expected type. This missing validation lets an attacker manipulate internal state that the component trusts.
Attack Vector
The attack vector is local. An attacker who already has a foothold on the host such as a low-privilege interactive or service account can trigger the vulnerable code path through the Mobile Broadband interface. See the Microsoft CVE-2025-29811 Advisory for vendor detail.
No public proof-of-concept exploit is currently listed for CVE-2025-29811, and the vulnerability is not on the CISA Known Exploited Vulnerabilities catalog.
Detection Methods for CVE-2025-29811
Indicators of Compromise
- Unexpected loading or interaction with Mobile Broadband driver components on systems without cellular hardware in use.
- Standard user processes obtaining SYSTEM tokens shortly after interacting with Mobile Broadband services.
- Crash or restart events tied to Mobile Broadband services followed by new privileged process creation.
Detection Strategies
- Monitor process creation chains where a standard user process spawns children running as SYSTEM without a legitimate elevation path.
- Correlate Windows Event Log entries for driver load events and service faults involving Mobile Broadband with subsequent privilege changes.
- Baseline Mobile Broadband API usage on servers and workstations, and alert on activity from processes that do not normally use cellular connectivity.
Monitoring Recommendations
- Ingest endpoint process, token, and driver telemetry into a centralized data lake for retrospective hunting across all Windows 11 and Windows Server 2022/2025 hosts.
- Track patch state per host and flag unpatched systems that generate Mobile Broadband service errors.
- Alert on privilege escalation patterns matching MITRE ATT&CK technique T1068 Exploitation for Privilege Escalation.
How to Mitigate CVE-2025-29811
Immediate Actions Required
- Apply the April 2025 Microsoft security updates that address CVE-2025-29811 to all affected Windows 11 and Windows Server builds.
- Prioritize patching on shared or multi-user hosts and on systems reachable through initial-access vectors such as email and web.
- Restrict interactive logon rights so that only necessary accounts can execute code locally on affected systems.
Patch Information
Microsoft has released security updates for all affected versions. Refer to the Microsoft CVE-2025-29811 Advisory for the current update packages that apply to each Windows 11 and Windows Server release listed above.
Workarounds
- On systems that do not use cellular connectivity, disable the Windows Mobile Broadband-related services to reduce exposure until patches are deployed.
- Enforce least privilege and remove unnecessary local accounts to limit which users can trigger the vulnerable code path.
- Use application control policies such as Windows Defender Application Control to block execution of unapproved binaries used to trigger the flaw.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
