How severe is CVE-2026-20857?

CVE-2026-20857 has a CVSS 3.x base score of 7.8, rated high severity. It is exploitable over local access with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2026-20857 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (37th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-20857?

CVE-2026-20857 primarily affects Microsoft Windows 10 1809. In total, 11 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2026-20857?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

Does CVE-2026-20857 have an EU (EUVD) identifier?

Yes. CVE-2026-20857 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-2174.

When was CVE-2026-20857 published?

CVE-2026-20857 was published on 2026-01-13 and last updated on 2026-06-17.

CVE-2026-20857

CVE-2026-20857 is a high-severity vulnerability in Microsoft Windows 10 1809 with a CVSS 3.x base score of 7.8. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-822.

Key facts

Severity: High (CVSS 3.x base score 7.8)
EPSS exploit prediction: 0% (37th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-2174
Weakness: CWE-822
Affected product: Microsoft Windows 10 1809
Published: 2026-01-13
Last modified: 2026-06-17

Description

Untrusted pointer dereference in Windows Cloud Files Mini Filter Driver allows an authorized attacker to elevate privileges locally.

Frequently asked questions

What is CVE-2026-20857?: Untrusted pointer dereference in Windows Cloud Files Mini Filter Driver allows an authorized attacker to elevate privileges locally.
How severe is CVE-2026-20857?: CVE-2026-20857 has a CVSS 3.x base score of 7.8, rated high severity. It is exploitable over local access with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2026-20857 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (37th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-20857?: CVE-2026-20857 primarily affects Microsoft Windows 10 1809. In total, 11 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2026-20857?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
Does CVE-2026-20857 have an EU (EUVD) identifier?: Yes. CVE-2026-20857 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-2174.
When was CVE-2026-20857 published?: CVE-2026-20857 was published on 2026-01-13 and last updated on 2026-06-17.

References

https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-20857

Affected products (11)

cpe:2.3:o:microsoft:windows_10_1809:*:*:*:*:*:*:x64:*
cpe:2.3:o:microsoft:windows_10_1809:*:*:*:*:*:*:x86:*
cpe:2.3:o:microsoft:windows_10_21h2:*:*:*:*:*:*:*:*
cpe:2.3:o:microsoft:windows_10_22h2:*:*:*:*:*:*:*:*
cpe:2.3:o:microsoft:windows_11_23h2:*:*:*:*:*:*:*:*
cpe:2.3:o:microsoft:windows_11_24h2:*:*:*:*:*:*:*:*
cpe:2.3:o:microsoft:windows_11_25h2:*:*:*:*:*:*:*:*
cpe:2.3:o:microsoft:windows_server_2019:*:*:*:*:*:*:*:*
cpe:2.3:o:microsoft:windows_server_2022:*:*:*:*:*:*:*:*
cpe:2.3:o:microsoft:windows_server_2022_23h2:*:*:*:*:*:*:*:*
cpe:2.3:o:microsoft:windows_server_2025:*:*:*:*:*:*:*:*

More vulnerabilities in Microsoft Windows 10 1809

CVE-2025-49708 — Critical (CVSS 9.9): Use after free in Microsoft Graphics Component allows an authorized attacker to elevate privileges over a network.
CVE-2026-47291 — Critical (CVSS 9.8): Integer overflow or wraparound in Windows HTTP.sys allows an unauthorized attacker to execute code over a network.
CVE-2026-44815 — Critical (CVSS 9.8): Stack-based buffer overflow in Windows DHCP Client allows an unauthorized attacker to execute code over a network.
CVE-2026-33824 — Critical (CVSS 9.8): Double free in Windows IKE Extension allows an unauthorized attacker to execute code over a network.
CVE-2025-60724 — Critical (CVSS 9.8): Heap-based buffer overflow in Microsoft Graphics Component allows an unauthorized attacker to execute code over a…
CVE-2025-53766 — Critical (CVSS 9.8): Heap-based buffer overflow in Windows GDI+ allows an unauthorized attacker to execute code over a network.

All CVEs affecting Microsoft Windows 10 1809 →

Other CWE-822 vulnerabilities

CVE-2025-50165 — Critical (CVSS 9.8): Untrusted pointer dereference in Microsoft Graphics Component allows an unauthorized attacker to execute code over a…
CVE-2023-1437 — Critical (CVSS 9.8): All versions prior to 9.1.4 of Advantech WebAccess/SCADA are vulnerable to use of untrusted pointers. The RPC arguments…
CVE-2026-48137 — Critical (CVSS 9.1): There is an untrusted pointer dereference vulnerability in the NI grpc-device sideband streaming API that may allow an…
CVE-2025-4993 — Critical (CVSS 9.1): Untrusted Pointer Dereference vulnerability in RTI Connext Professional (Core Libraries) allows Pointer…
CVE-2025-1255 — Critical (CVSS 9.1): Untrusted Pointer Dereference vulnerability in RTI Connext Professional (Core Libraries) allows Pointer…
CVE-2024-36461 — Critical (CVSS 9.1): Within Zabbix, users have the ability to directly modify memory pointers in the JavaScript engine.

Browse all CWE-822 vulnerabilities →