CVE-2025-49687: Windows 10 Privilege Escalation Flaw

CVE-2025-49687 Overview

CVE-2025-49687 is an out-of-bounds read vulnerability [CWE-125] in the Microsoft Input Method Editor (IME) component shipped with supported versions of Windows and Windows Server. An authenticated local attacker can leverage the flaw to elevate privileges on an affected system. Microsoft addressed the issue in the July 2025 Patch Tuesday cycle. The vulnerability affects a wide range of client and server SKUs, including Windows 10, Windows 11, and Windows Server releases from 2012 through 2025.

Critical Impact
Successful exploitation allows a low-privileged local user to escalate privileges with a scope change, resulting in high impact to confidentiality, integrity, and availability across the compromised host.

Affected Products

Microsoft Windows 10 (versions 1507, 1607, 1809, 21H2, 22H2)
Microsoft Windows 11 (versions 22H2, 23H2, 24H2)
Microsoft Windows Server 2012, 2016, 2019, 2022, 2022 23H2, and 2025

Discovery Timeline

2025-07-08 - CVE-2025-49687 published to NVD and Microsoft releases security update
2026-06-17 - Last updated in NVD database

Technical Details for CVE-2025-49687

Vulnerability Analysis

The vulnerability is an out-of-bounds read in the Microsoft Input Method Editor (IME) subsystem. IME components run within user sessions and interact with higher-privileged system services to translate keyboard input into localized text for languages such as Japanese, Chinese, and Korean. When IME processes malformed input data, it reads memory outside the intended buffer boundary. An authorized local attacker can craft input that triggers this read to leak sensitive memory contents or influence downstream logic, enabling privilege escalation with a scope change to protected components.

Root Cause

The root cause is missing or insufficient bounds validation in an IME routine that parses attacker-influenced buffers. The affected code does not verify that read offsets remain within the allocated region before dereferencing, resulting in an out-of-bounds read classified under [CWE-125]. Reading past the boundary exposes adjacent kernel or process memory that the caller is not authorized to access.

Attack Vector

Exploitation requires local access and a low-privileged authenticated session on the target host. The attacker interacts with the IME interface, submitting crafted input that triggers the vulnerable read path. Because the CVSS scope is changed, the impact extends beyond the vulnerable component into the surrounding security context, allowing the attacker to gain elevated privileges. No user interaction is required beyond the attacker's own actions on the host.

Specific proof-of-concept code is not publicly available. Refer to the Microsoft Security Update Guide for CVE-2025-49687 for vendor-supplied technical details.

Detection Methods for CVE-2025-49687

Indicators of Compromise

Unexpected process token elevation events originating from user sessions where IME (imjp*.dll, imkr*.dll, imtc*.dll, or imsc*.dll) modules are loaded.
Abnormal crashes or hangs in processes hosting IME components, such as ctfmon.exe or user-mode input services, which may indicate exploitation attempts.
New or unfamiliar child processes spawned under elevated integrity levels shortly after IME activity.

Detection Strategies

Monitor for anomalous privilege escalation chains that correlate IME-related module loads with subsequent token manipulation or SYSTEM-context activity.
Alert on process crashes with access violation exceptions in IME DLLs, which can indicate exploitation attempts against the out-of-bounds read.
Use behavioral analytics to identify low-privileged users triggering activity that culminates in administrative or SYSTEM-level operations without a known escalation path.

Monitoring Recommendations

Enable Windows Security event auditing for privilege use (Event IDs 4672, 4673, 4674) on all endpoints and servers.
Collect Windows Error Reporting and application crash telemetry from IME-hosting processes into a centralized data lake for retrospective hunting.
Track patch deployment status across all Windows client and server SKUs listed in the affected products, prioritizing multi-user systems such as terminal servers.

How to Mitigate CVE-2025-49687

Immediate Actions Required

Apply the July 2025 Microsoft security updates to all affected Windows 10, Windows 11, and Windows Server versions immediately.
Prioritize patching multi-user hosts, Remote Desktop Session Hosts, and Virtual Desktop Infrastructure where local attackers are more likely to gain a foothold.
Audit local account inventories and remove unnecessary interactive login rights to reduce the attack surface for local privilege escalation.

Patch Information

Microsoft released fixes for CVE-2025-49687 through the standard Windows Update channel on July 8, 2025. Consult the Microsoft Security Update Guide for CVE-2025-49687 for the KB article numbers that correspond to each affected Windows and Windows Server build.

Workarounds

No official vendor workaround is published; applying the security update is the supported remediation path.
Restrict interactive and Remote Desktop logon rights on sensitive systems to trusted administrators until patching is complete.
On systems that do not require East Asian language input, consider removing unused IME language packs to reduce exposed code paths.

bash

# Verify installed updates on a Windows host
wmic qfe list brief /format:table

# Or with PowerShell
Get-HotFix | Sort-Object -Property InstalledOn -Descending | Select-Object -First 20