CVE-2026-50383: Windows Print Spooler Information Disclosure

CVE-2026-50383 Overview

CVE-2026-50383 is a buffer over-read vulnerability in Windows Print Spooler Components. An authorized local attacker can exploit the flaw to disclose sensitive information from process memory. Microsoft published the advisory on July 14, 2026.

The issue is categorized under [CWE-126: Buffer Over-read]. Exploitation requires local access and low privileges, with no user interaction needed. The vulnerability affects confidentiality primarily, with limited impact on availability and no impact on integrity.

Critical Impact
An authenticated local attacker can read memory contents beyond intended buffer boundaries within Windows Print Spooler, exposing information that may aid subsequent attacks.

Affected Products

Windows Print Spooler Components (see Microsoft Security Update CVE-2026-50383 for the current list of affected Windows versions and builds)

Discovery Timeline

2026-07-14 - CVE-2026-50383 published to NVD
2026-07-15 - Last updated in NVD database

Technical Details for CVE-2026-50383

Vulnerability Analysis

The vulnerability resides in Windows Print Spooler Components, a subsystem responsible for managing print jobs, printer drivers, and related interprocess communication. A buffer over-read condition allows a local, authenticated attacker to read memory outside of the intended buffer boundary.

Buffer over-reads occur when code reads past the end of a buffer while processing input or internal data structures. In the Print Spooler context, this can expose adjacent memory contents to a caller who supplies crafted input to a spooler interface. Disclosed data may include pointers, handles, or fragments of other process memory useful for bypassing address space layout randomization (ASLR) or staging further exploitation.

The EPSS score is 0.296% at the 21.685 percentile, reflecting a low likelihood of broad exploitation attempts in the near term. No public exploit has been reported, and the issue is not listed on the CISA Known Exploited Vulnerabilities catalog.

Root Cause

The root cause is improper validation of a buffer length or index within Print Spooler code paths. When the component processes a request, it reads more bytes than the source buffer contains. The condition maps to [CWE-126: Buffer Over-read], typically caused by missing bounds checks, incorrect size calculations, or mismatches between declared and actual buffer sizes.

Attack Vector

Exploitation requires local access to a Windows host with the Print Spooler service running. The attacker must hold at least low privileges on the system before triggering the vulnerable code path. The attacker interacts with a Print Spooler interface using crafted input that induces the over-read. The service returns or logs data containing memory contents beyond the intended buffer, which the attacker retrieves for reconnaissance or chaining with other flaws.

Refer to the Microsoft Security Update CVE-2026-50383 advisory for authoritative technical details.

Detection Methods for CVE-2026-50383

Indicators of Compromise

Unusual process activity from spoolsv.exe or Print Spooler-related child processes on hosts where printing is not routinely used.
Repeated calls to Print Spooler RPC interfaces from a single low-privileged user session.
Anomalous crashes or access violations logged for spoolsv.exe in the Windows Application event log.

Detection Strategies

Monitor for local process interactions with the Print Spooler service originating from non-administrative user contexts.
Correlate Print Spooler activity with subsequent privilege escalation attempts or credential access behavior on the same endpoint.
Track patch state across Windows endpoints and flag systems missing the update associated with CVE-2026-50383.

Monitoring Recommendations

Enable Windows Print Service operational logging under Microsoft-Windows-PrintService/Operational to capture spooler activity.
Ingest endpoint telemetry into a centralized analytics platform to detect low-and-slow reconnaissance across hosts.
Alert on repeated non-fatal spooler errors that may indicate probing for over-read conditions.

How to Mitigate CVE-2026-50383

Immediate Actions Required

Apply the Microsoft security update referenced in the Microsoft Security Update CVE-2026-50383 advisory to all affected Windows systems.
Inventory Windows endpoints and servers where the Print Spooler service is enabled and prioritize patching for high-value hosts.
Restrict interactive and remote logon rights on servers to reduce the local attacker population.

Patch Information

Microsoft has released a security update addressing CVE-2026-50383. Consult the Microsoft Security Update CVE-2026-50383 guidance for the specific KB articles and build numbers corresponding to each supported Windows release.

Workarounds

On systems that do not require printing, disable the Print Spooler service to remove the attack surface entirely.
Limit membership in local groups that grant interactive logon on servers hosting the Print Spooler service.
Apply application control policies that restrict which users can invoke printing-related utilities on sensitive hosts.

bash

# Disable the Print Spooler service on systems that do not require printing
Stop-Service -Name Spooler -Force
Set-Service -Name Spooler -StartupType Disabled