CVE-2026-56649
HIGHCVSS 8.1/10EPSS 0.65%
Last modified
CVE-2026-56649 is a high-severity vulnerability rated 8.1/10 on the CVSS scale. Concurrent execution using shared resource with improper synchronization ('race condition') in Windows Network File System allows an unauthorized attacker to execute code over a network.. EPSS estimates a 0.65% chance of exploitation in the next 30 days.
Description
Concurrent execution using shared resource with improper synchronization ('race condition') in Windows Network File System allows an unauthorized attacker to execute code over a network.
Metrics
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
Weakness Enumeration
Affected Software
| Vendor | Product | Versions |
|---|---|---|
| Microsoft | Windows 10 1607 | < 10.0.14393.9339 |
| Microsoft | Windows 10 1809 | < 10.0.17763.9020 |
| Microsoft | Windows 10 21h2 | < 10.0.19044.7548 |
| Microsoft | Windows 10 22h2 | < 10.0.19045.7548 |
| Microsoft | Windows 11 24h2 | < 10.0.26100.8875 |
| Microsoft | Windows 11 25h2 | < 10.0.26200.8875 |
| Microsoft | Windows 11 26h1 | < 10.0.28000.2269 |
| Microsoft | Windows Server 2012 | All versions |
| Microsoft | Windows Server 2012 | r2 |
| Microsoft | Windows Server 2016 | < 10.0.14393.9339 |
| Microsoft | Windows Server 2019 | < 10.0.17763.9020 |
| Microsoft | Windows Server 2022 | < 10.0.20348.5386 |
| Microsoft | Windows Server 2025 | < 10.0.26100.33158 |
References
- https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-56649Patch, Vendor Advisory
Timeline
- Published
- Last Modified
- Status
- Analyzed
Frequently Asked Questions
What is CVE-2026-56649?
Concurrent execution using shared resource with improper synchronization ('race condition') in Windows Network File System allows an unauthorized attacker to execute code over a network.
How severe is CVE-2026-56649?
CVE-2026-56649 has a CVSS score of 8.1/10 (HIGH severity). The EPSS model estimates a 0.65% probability of exploitation in the next 30 days.
How do I fix CVE-2026-56649?
Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.
How Strix Helps
- How Strix found a critical auth bypass in etcdStrix autonomously discovered a critical authentication bypass in etcd, later designated CVE-2026-33413.
- Autonomous PentestingAI agents that find and validate exploitable vulnerabilities like this one across your applications.
- PR ReviewsPentest every pull request so vulnerable code is caught before it ships to production.
- AI Penetration TestingHow AI-driven penetration testing continuously covers your attack surface.
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Are you affected by CVE-2026-56649?
Run a free Strix scan to check your systems for this vulnerability.
Scan your code nowSource: NVD / NIST