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CVE-2026-42900

HIGH 8.1

Published 2026-07-14 · Last modified 2026-07-21

Concurrent execution using shared resource with improper synchronization ('race condition') in Windows App Store allows an unauthorized attacker to elevate privileges over a network.

ELEVATED IMPACT

Severe if exploited (CVSS 8.1), but no known exploitation and low modeled probability. Patch on a normal cadence.

Exploitation likelihood

0.4%chance of exploitation in 30 days · 31st percentile

○ In CISA KEV ○ Public exploit / PoC

Impact if exploited

8.1CVSS 3.1 · HIGH

  • ConfidentialityHigh
  • IntegrityHigh
  • AvailabilityHigh

What an attacker needs

  • ✓Access: Reachable over the network — no local access needed
  • ✓Privileges: No account or privileges required
  • ✓User interaction: No user interaction needed
  • ⚠Complexity: Needs a race window or specific setup

✓ lowers the bar for an attacker · ⚠ raises it

Proof of concept & exploit code

Test against your own equipment

curl -s https://vulnpedia.com/cve/CVE-2026-42900/poc.jsonMachine-readable PoC index for this CVE (for automation).

Listed for defensive triage, patch verification, and authorized testing on systems you own. Machine-readable: /cve/CVE-2026-42900/poc.json

Affected

Vendors Microsoft

Products Windows 10 Version 1607 Windows 10 Version 1809 Windows 10 Version 21h2 Windows 10 Version 22h2 Windows 11 Version 24h2 Windows 11 Version 25h2 Windows 11 Version 26h1 Windows Server 2016 Windows Server 2016 (Server Core Installation) Windows Server 2019 Windows Server 2019 (Server Core Installation) Windows Server 2022

Weakness (CWE)

  • CWE-362: : Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')
  • CWE-416: : Use After Free

CVSS vector

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C

Known Affected Software Configurations

VendorProductVersion range
MicrosoftWindows 10 1607< 10.0.14393.9339
MicrosoftWindows 10 1607< 10.0.14393.9339
MicrosoftWindows 10 1809< 10.0.17763.9020
MicrosoftWindows 10 1809< 10.0.17763.9020
MicrosoftWindows 10 21h2< 10.0.19044.7548
MicrosoftWindows 10 21h2< 10.0.19044.7548
MicrosoftWindows 10 21h2< 10.0.19044.7548
MicrosoftWindows 10 22h2< 10.0.19045.7548
MicrosoftWindows 10 22h2< 10.0.19045.7548
MicrosoftWindows 10 22h2< 10.0.19045.7548
MicrosoftWindows 11 24h2< 10.0.26100.8875
MicrosoftWindows 11 24h2< 10.0.26100.8875
MicrosoftWindows 11 25h2< 10.0.26200.8875
MicrosoftWindows 11 25h2< 10.0.26200.8875
MicrosoftWindows 11 26h1< 10.0.28000.2269
MicrosoftWindows 11 26h1< 10.0.28000.2269
MicrosoftWindows Server 2016< 10.0.14393.9339
MicrosoftWindows Server 2019< 10.0.17763.9020
MicrosoftWindows Server 2022< 10.0.20348.5386
MicrosoftWindows Server 2025< 10.0.26100.33158

All CVSS metrics

  • HIGH 8.1 v3.1 · CNA Primary
    CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C
  • HIGH 8.1 v3.1 · NVD Secondary
    CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H

References

Patches & mitigations

Sources: NVD · CVE.org · EPSS