How severe is CVE-2026-20837?

CVE-2026-20837 has a CVSS 3.x base score of 7.8, rated high severity. It is exploitable over local access with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2026-20837 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (47th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-20837?

CVE-2026-20837 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-2026-20837?

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-2026-20837 have an EU (EUVD) identifier?

Yes. CVE-2026-20837 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-2180.

When was CVE-2026-20837 published?

CVE-2026-20837 was published on 2026-01-13 and last updated on 2026-06-17.

CVE-2026-20837

CVE-2026-20837 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-122.

Key facts

Severity: High (CVSS 3.x base score 7.8)
EPSS exploit prediction: 1% (47th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-2180
Weakness: CWE-122
Affected product: Microsoft Windows 10 1809
Published: 2026-01-13
Last modified: 2026-06-17

Description

Heap-based buffer overflow in Windows Media allows an unauthorized attacker to execute code locally.

Frequently asked questions

What is CVE-2026-20837?: Heap-based buffer overflow in Windows Media allows an unauthorized attacker to execute code locally.
How severe is CVE-2026-20837?: CVE-2026-20837 has a CVSS 3.x base score of 7.8, rated high severity. It is exploitable over local access with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2026-20837 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (47th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-20837?: CVE-2026-20837 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-2026-20837?: 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-2026-20837 have an EU (EUVD) identifier?: Yes. CVE-2026-20837 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-2180.
When was CVE-2026-20837 published?: CVE-2026-20837 was published on 2026-01-13 and last updated on 2026-06-17.

References

https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-20837

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:*:*:*:*:*:*:*:*

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