Severity by source
AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Local authenticated access (AV:L/PR:L); AC:H because a race condition requires winning a narrow timing window; full SYSTEM compromise gives C/I/A:H.
Primary rating from Vendor (microsoft).
CVSS VectorVendor: microsoft
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Lifecycle Timeline
2DescriptionCVE.org
Concurrent execution using shared resource with improper synchronization ('race condition') in Windows USB Print Driver allows an authorized attacker to elevate privileges locally.
AnalysisAI
Local privilege escalation in the Windows USB Print Driver lets an already-authenticated low-privileged user win a race condition to gain SYSTEM-level control on Windows 11 (24H2, 25H2, 26H1) and Windows Server 2025. The flaw stems from unsynchronized access to a shared resource, and successful exploitation yields full confidentiality, integrity, and availability impact. …
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Attack ChainAIDerived
Hypothetical attack flow derived from CVE metadata
Vulnerability AssessmentAI
| Exploitation | The attacker must already have a valid low-privileged local account and interactive execution on the target (CVSS PR:L, AV:L) - this is a local elevation-of-privilege flaw, not remotely reachable. … Additional conditions and limiting factors are described in the full assessment. |
| Risk Assessment | The provided CVSS 3.1 vector (AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H, base 7.8 High) frames this as a locally-exploitable elevation-of-privilege issue requiring existing low-level access but no user interaction, with full triple-impact. … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in. |
| Exploit Scenario | A standard user who already has a foothold on a workstation - through phishing, a compromised low-privilege service account, or shared kiosk access - runs a tool that repeatedly triggers the USB print driver while racing a second thread to manipulate the shared resource during its unsynchronized window. Winning the race corrupts privileged state and hands the attacker SYSTEM-level execution, converting limited access into full host compromise. … |
| Remediation | Patch available per vendor advisory - apply the Microsoft security update for CVE-2026-54991 to all affected Windows 11 (24H2/25H2/26H1) and Windows Server 2025 systems, obtaining exact fixed build numbers from the MSRC guide at https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-54991 (no specific fixed version string was included in the intelligence, so confirm it there before deployment). … Detailed patch versions, workarounds, and compensating controls in full report. |
Recommended ActionAI
Within 24 hours, deploy the Microsoft-released patch for CVE-2026-54991 to all production Windows 11 (24H2, 25H2, 26H1) and Windows Server 2025 systems. …
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External POC / Exploit Code
Leaving vuln.today
EUVD-2026-44005
GHSA-wf5r-2qwx-c42p