CVE-2026-49803: Windows AppX Deployment Extensions Elevation of Privilege Vulnerability

highCVSS 7CVE-2026-49803

Concurrent execution using shared resource with improper synchronization ('race condition') in Windows AppX Deployment Service allows an authorized attacker to elevate privileges locally.

CSIRTS triage

vendor: Microsoft product: Windows Privilege escalation

What: Concurrent execution using shared resource with improper synchronization ('race condition') in Windows AppX Deployment Service allows an authorized attacker to elevate privileges locally.
Who is affected: Authorized attackers on affected Windows systems.
Urgency: Remediation is urgent due to high severity and potential for local privilege escalation.
Action: Apply the latest security patch for Windows.

AI-assisted analysis generated from the source advisory — verify against the original.

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Details

Source: Microsoft Security Response Center (INTL · vendor-psirt · site)
Severity: high — CVSS 7
Published: 2026-07-14
Exploitation: Not in CISA KEV at last sync

Original advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-49803

Exploitation outlook

EPSS (FIRST.org) estimates each CVE’s probability of exploitation in the next 30 days — here is the CSIRTS.com read on those numbers.

Low exploitation riskCVE-2026-498030.15% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 5% of all scored CVEs.

Referenced CVEs

CVE	CSIRTS overview	External
CVE-2026-49803	coverage & exploitation status	NVD · CVE.org

Same CVEs, other sources

How other CERTs, PSIRTs and databases cover the vulnerabilities in this advisory.

critical[NEW] [critical] Microsoft Windows products: Multiple vulnerabilitiescert-bund
unknownexploitedNCSC-2026-0231 [1.00] [M/H] Vulnerabilities fixed in Microsoft Windowsncsc-nl
highCVE-2026-49803: Concurrent execution using shared resource with improper synchronization ('race condition') in…nvd

Recent advisories for Windows AppX Deployment

A cluster of recent advisories against the same product widens the attack surface — attackers routinely chain freshly published CVEs on one product, so review these together.

highCVE-2026-49803: Concurrent execution using shared resource with improper synchronization ('race condition') in…nvd · 2026-07-14
criticalexploitedCVE-2019-1130: Microsoft Windows AppX Deployment Service Privilege Escalation Vulnerabilitycisa-kev · 2022-05-23
criticalexploitedCVE-2019-1385: Microsoft Windows AppX Deployment Extensions Privilege Escalation Vulnerabilitycisa-kev · 2022-05-23
criticalexploitedCVE-2019-1064: Microsoft Windows AppX Deployment Service (AppXSVC) Privilege Escalation Vulnerabilitycisa-kev · 2022-03-15
criticalexploitedCVE-2019-1253: Microsoft Windows AppX Deployment Server Privilege Escalation Vulnerabilitycisa-kev · 2022-03-15
criticalexploitedCVE-2019-1129: Microsoft Windows AppX Deployment Service (AppXSVC) Privilege Escalation Vulnerabilitycisa-kev · 2022-03-15