CVE-2026-50377 Overview
CVE-2026-50377 is an out-of-bounds read vulnerability in the Windows Kernel that allows an authorized local attacker to elevate privileges. The flaw is tracked under CWE-125 and requires local access with low privileges to exploit. Successful exploitation exposes sensitive kernel memory contents, which an attacker can leverage to bypass kernel security mechanisms and escalate privileges on the affected host. Microsoft documented the issue in the Microsoft CVE-2026-50377 Advisory.
Critical Impact
An authenticated local attacker can read out-of-bounds kernel memory to disclose sensitive data, enabling privilege escalation on Windows systems.
Affected Products
- Microsoft Windows (Kernel component) — refer to the Microsoft advisory for the full list of affected builds
Discovery Timeline
- 2026-07-14 - CVE-2026-50377 published to NVD
- 2026-07-15 - Last updated in NVD database
Technical Details for CVE-2026-50377
Vulnerability Analysis
The vulnerability is an out-of-bounds read [CWE-125] in the Windows Kernel. When the kernel processes a specific input or request from a low-privileged user-mode caller, it reads memory beyond the intended buffer boundary. This exposes adjacent kernel memory contents to the attacker.
Disclosed kernel memory often contains pointers, tokens, or structure fields that defeat Kernel Address Space Layout Randomization (KASLR). An attacker who collects this information can chain it with other primitives to modify kernel objects and achieve privilege escalation. The confidentiality impact is high while integrity and availability are unaffected, consistent with a read-only memory disclosure primitive.
Exploitation requires local access and valid credentials on the target system. No user interaction is required, and the scope remains unchanged within the kernel security boundary. The EPSS probability is approximately 0.397%, reflecting a low near-term likelihood of broad exploitation.
Root Cause
The root cause is missing or insufficient bounds validation on a buffer or index used by a kernel routine. The kernel dereferences memory outside the allocated region, returning attacker-observable bytes from adjacent kernel structures.
Attack Vector
The attack vector is local. An authenticated attacker executes a crafted user-mode program that issues a system call or IOCTL to the vulnerable kernel path. The kernel returns out-of-bounds data to the caller, which the attacker parses to extract sensitive kernel state. No verified public proof-of-concept code is available at this time. Refer to the Microsoft CVE-2026-50377 Advisory for authoritative technical details.
Detection Methods for CVE-2026-50377
Indicators of Compromise
- Unexpected user-mode processes issuing repeated or malformed system calls or IOCTLs to kernel components
- Unsigned or newly introduced binaries executing from user-writable directories such as %TEMP% or %APPDATA%
- Sudden token or integrity-level changes for processes launched by standard users
Detection Strategies
- Monitor for anomalous process behavior where a low-privileged process spawns a child running with SYSTEM or elevated integrity
- Correlate driver load events and kernel error telemetry with subsequent privilege changes on the same host
- Baseline expected system call patterns for standard user sessions and alert on statistical deviations
Monitoring Recommendations
- Enable Windows Security, System, and Sysmon event channels and forward them to a central analytics platform
- Track Event ID 4688 (process creation) with command-line auditing enabled to identify suspicious local exploitation attempts
- Alert on integrity-level transitions from Medium to High or System for processes started by non-administrative users
How to Mitigate CVE-2026-50377
Immediate Actions Required
- Apply the Microsoft security update referenced in the Microsoft CVE-2026-50377 Advisory as soon as it is available in your patch cycle
- Restrict local logon rights and enforce least-privilege on multi-user systems, terminal servers, and virtual desktop infrastructure
- Audit local accounts and disable dormant users to reduce the pool of principals that satisfy the authentication requirement
Patch Information
Microsoft addresses this vulnerability through its monthly security update channel. Consult the Microsoft CVE-2026-50377 Advisory for the specific KB numbers and affected Windows builds, then deploy the corresponding updates through Windows Update, WSUS, or your configuration management platform.
Workarounds
- No vendor-supplied workaround is currently documented; apply the security update as the primary remediation
- Reduce interactive and remote local logon exposure by enforcing strong authentication and network segmentation
- Use application control policies such as Windows Defender Application Control or AppLocker to block unauthorized binaries from executing on sensitive hosts
# Configuration example: verify patch installation status on Windows hosts
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Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
