CVE-2026-50343: CVE-2026-50343: Improper privilege management in Microsoft Install Service allows an authorized attacker t…

What it is

Improper privilege management in Microsoft Install Service allows an authorized attacker to elevate privileges locally.

Exploitation evidence

First exploit evidence seen: 2026-07-14 (earliest date across the sources below).

Exploited in the wild

No source on this site lists in-the-wild exploitation yet (CISA KEV, VulnCheck KEV).

Public exploit code

GitHub proof-of-concept repositories

1 public repositories from 1 accounts, first seen 2026-07-14. Most starred: Rat5ak/CVE-2026-50343-InstallService-EoP (48 stars), view repository.

Verify before running: public PoCs can be malicious. Read the code and only run it in an isolated lab. A PoC means exploit code is public, not that this CVE is exploited in the wild.

Sources: nomi-sec/PoC-in-GitHub.

How to fix it

Fixed versions

• microsoft windows 10 1809: upgrade to 10.0.17763.9020 or later
• microsoft windows 10 21h2: upgrade to 10.0.19044.7548 or later
• microsoft windows 10 22h2: upgrade to 10.0.19045.7548 or later
• microsoft windows 11 24h2: upgrade to 10.0.26100.8875 or later
• microsoft windows 11 25h2: upgrade to 10.0.26200.8875 or later
• microsoft windows 11 26h1: upgrade to 10.0.28000.2269 or later
• microsoft windows 11 26h1: upgrade to 10.0.28000.2525 or later
• microsoft windows server 2019: upgrade to 10.0.17763.9020 or later
• microsoft windows server 2022: upgrade to 10.0.20348.5386 or later
• microsoft windows server 2025: upgrade to 10.0.26100.33158 or later

Derived from the NVD CPE configuration (versionEndExcluding / versionEndIncluding). Always confirm with the vendor advisory.

Vendor advisories and patches

• https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-50343 (Patch, Vendor Advisory)

MITRE ATT&CK mitigations for this chain

• M1051 Update Software (for T1068) : Update software regularly by employing patch management for internal enterprise endpoints and servers.
• M1050 Exploit Protection (for T1068) : Security applications that look for behavior used during exploitation such as Windows Defender Exploit Guard (WDEG) and the Enhanced Mitigation Experience Toolkit (EMET) can be used to mitigate some exploitation behavior. Control flow integrity checking is another way to potentially identify and stop a software exploi
• M1048 Application Isolation and Sandboxing (for T1068) : Make it difficult for adversaries to advance their operation through exploitation of undiscovered or unpatched vulnerabilities by using sandboxing. Other types of virtualization and application microsegmentation may also mitigate the impact of some types of exploitation. Risks of additional exploits and weaknesses in t
• M1019 Threat Intelligence Program (for T1068) : Develop a robust cyber threat intelligence capability to determine what types and levels of threat may use software exploits and 0-days against a particular organization.
• M1038 Execution Prevention (for T1068) : Consider blocking the execution of known vulnerable drivers that adversaries may exploit to execute code in kernel mode. Validate driver block rules in audit mode to ensure stability prior to production deployment.

Detection Generic guidance

• Privilege Escalation: Alert on processes gaining SYSTEM/root unexpectedly, and on exploitation crashes of privileged services.

Response checklist Generic guidance

1. Inventory: find every instance of the affected product and version (include internet-facing and forgotten ones).
2. Patch or mitigate per the vendor advisory; if you cannot patch, remove internet exposure or apply the vendor workaround.
3. Assume compromise if the system was exposed before patching: hunt for the indicators in the advisory and review logs back to the disclosure date.
4. Rotate credentials and secrets stored on or used by the affected system if compromise cannot be ruled out.