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How CVE-2026-54996 Works
CVE-2026-54996 is a race condition vulnerability residing in the Windows USB Print Driver component (usbprint.sys). The flaw stems from improper synchronization when the driver handles concurrent execution threads that access a shared resource—specifically, internal kernel-mode data structures used to manage USB printer I/O requests.
Under normal operation, the USB Print Driver processes print jobs and device control commands via IOCTL (Input/Output Control) requests sent from user-mode applications through the `DeviceIoControl` API. The driver exposes several IOCTL handlers, including `SET_PROTOCOL` (0x220048) and others, that are marked as `METHOD_BUFFERED` and FILE_ANY_ACCESS. These handlers are reachable from any local interactive user who has handle access to the printer device interface.
The core problem is that these IOCTL handlers do not properly lock or serialize access to shared kernel resources when multiple threads concurrently invoke them. An authorized local attacker—already authenticated on the system—can craft a sequence of `DeviceIoControl` calls that deliberately trigger this race window. By timing two or more concurrent operations that manipulate the same shared memory region or driver state, the attacker can cause the driver to read or write data in an inconsistent state.
This race condition manifests in several ways:
- Use-after-free scenarios where one thread frees a kernel object while another thread still holds a reference to it.
- Double-fetch vulnerabilities where the driver reads a value from user memory, validates it, then reads it again later without re-validation, allowing a concurrent thread to change the value in between.
- Out-of-bounds reads (CWE-125) when the driver uses a corrupted length or index value due to the race.
The exploitation does not require user interaction and can be performed entirely from the local console or via a locally executed malicious binary. The attack complexity is rated HIGH because the attacker must win a precise timing race, but successful exploitation grants the attacker full SYSTEM-level privileges, allowing them to read sensitive data, modify system files, install persistent backdoors, or completely compromise the host.
Microsoft patched this vulnerability in the July 2026 Patch Tuesday updates, released on July 14, 2026. The fix introduces proper synchronization primitives—such as mutexes or spinlocks—around the critical sections of the driver code, ensuring that concurrent access to shared resources is serialized safely.
DailyCVE Form:
Platform: ……. Windows 11 24H2/25H2/26H1, Server 2025
Version: …….. 10.0.26100, 10.0.26200, 10.0.28000
Vulnerability :.. Race Condition (CWE-362, CWE-125)
Severity: ……. HIGH (CVSS 3.1: 7.0)
date: ……….. 2026-07-14
Prediction: ….. Patch available (July 2026 updates)
What Undercode Say:
Analytics:
- CVSS 3.1 Base Score: 7.0 (HIGH) – Vector: AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
- Exploit Availability: No public exploit as of July 2026
- Exploit Price Estimate: $5,000 – $25,000 USD
- CISA Assessment: Exploitation: none | Automatable: no | Technical Impact: total
- Affected Products: Windows 11 24H2 (< 10.0.26100.8875), 25H2 (< 10.0.26200.8875), 26H1 (< 10.0.28000.2525), Server 2025 (< 10.0.26100.33158)
Bash / Commands (local enumeration & detection):
Check Windows version and build number systeminfo | findstr /B /C:"OS Name" /C:"OS Version" Verify installed KB patches (July 2026 cumulative update) wmic qfe list brief | findstr "KB5040437" example KB, replace with actual List loaded USB print driver details driverquery /v | findstr usbprint.sys Check driver file version powershell -command "(Get-Item C:\Windows\System32\drivers\usbprint.sys).VersionInfo.FileVersion"
Exploit:
A local attacker with low-privileged credentials can execute a malicious program that repeatedly calls `DeviceIoControl` on the printer device handle (\\.\USBPRINT) with crafted input buffers. By spawning multiple threads that race to modify shared memory, the attacker corrupts kernel pointers and gains arbitrary read/write in kernel space, ultimately spawning a SYSTEM shell. No public exploit code has been released, but the vulnerability is considered easy to trigger once the race window is understood.
Protection:
- Apply the July 2026 cumulative security update from Microsoft Update or Windows Update.
- Restrict local access to the USB printer device interface via Group Policy or ACLs (though this is a partial mitigation).
- Enable Windows Defender Attack Surface Reduction (ASR) rules to block `DeviceIoControl` calls from untrusted applications.
- Monitor for unusual `DeviceIoControl` activity targeting `\\.\USBPRINT` using Sysmon or EDR solutions.
Impact:
Successful exploitation allows an authenticated local attacker to elevate privileges to SYSTEM level, compromising the confidentiality, integrity, and availability of the entire host. The attacker can read encrypted data, install malware, create backdoor accounts, disable security software, and pivot to other systems on the network. Given the local attack vector and the need for precise timing, the immediate risk to enterprise environments is moderate, but the potential impact is severe.
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Sources:
Reported By: nvd.nist.gov
Extra Source Hub:
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