Quick answer
Direct answer
Risk scores
| CVSS metric | What it means |
|---|---|
| Attack vector (AV:L) | Local access needed |
| Attack complexity (AC:L) | Low complexity |
| Privileges required (PR:N) | No privileges required |
| User interaction (UI:N) | No user interaction |
| Scope (S:U) | Scope unchanged |
| Confidentiality (C:H) | High confidentiality impact |
| Integrity (I:H) | High integrity impact |
| Availability (A:H) | High availability impact |
CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
About Microsoft Windows 10 1607
CVE-2026-77503 affects Microsoft Windows 10 1607, a product from Microsoft. Before acting, confirm where Microsoft Windows 10 1607 runs in your estate, who owns it and whether it is reachable from the internet, because exposure decides real risk more than the score alone.
What the flaw is
In plain terms: Out-of-bounds read in Windows NTFS allows an unauthorized attacker to elevate privileges locally.
The weakness class is Out of Bounds Read. The program reads memory past the end of a buffer, leaking data or crashing.
Based on its CVSS vector, the flaw needs local or adjacent access, needs no login, and needs no user interaction. Apply the vendor fix and confirm exposure on internet facing and business critical assets first.
Affected versions and timeline
| Field | Detail |
|---|---|
| Product | Microsoft Windows 10 1607 |
| Affected versions | Windows 10 1607 before 10.0.14393.9512; Windows 10 1809 before 10.0.17763.9245; Windows 10 21h2 before 10.0.19044.7725; Windows 10 22h2 before 10.0.19045.7725; Windows 11 23h2 before 10.0.22631.7582; Windows 11 24h2 before 10.0.26100.9445; Windows 11 25h2 before 10.0.26200.9445; Windows 11 26h1 before 10.0.28000.2954; Windows Server 2012 all listed versions; Windows Server 2012 r2; Windows Server 2016 before 10.0.14393.9512; Windows Server 2019 before 10.0.17763.9245 |
| Published | Sep 8, 2026 |
| Last modified | Sep 24, 2026 |
| Added to CISA KEV | Not listed |
| Assigning CNA | secure@microsoft.com |
How to detect it
- Inventory every instance of Microsoft Windows 10 1607 and record the running version against the affected range above.
- Check external attack surface scans for internet facing instances of the component.
- Review logs on affected systems for unusual requests, errors or new processes around the vulnerable function.
- Confirm with an authenticated vulnerability scan once your scanner has a check for this CVE.
How to fix it
- Apply the fixed version of Microsoft Windows 10 1607 named in the vendor advisory.
- If patching must wait, restrict network access to the affected service and put it behind authentication or a web application firewall rule.
- Rescan after the change to prove the exposure is gone, then close the ticket.
CTEM action plan
| CTEM stage | What to do for this CVE |
|---|---|
| Scope | Add every business service that depends on Microsoft Windows 10 1607 to the current CTEM cycle. |
| Discover | Find all instances, including shadow and cloud deployments, and record versions and exposure. |
| Prioritize | Rank using EPSS and CVSS together with asset exposure and business impact. |
| Validate | Confirm the flaw is reachable and exploitable in your environment and that compensating controls work. |
| Mobilize | Assign the fix to the asset owner with a due date matched to the priority, then verify closure. |
CWE References
- CWE-125: Out of Bounds Read More CVEs with this weakness
Technical References
Frequently asked questions
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