How severe is CVE-2026-20849?

CVE-2026-20849 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with high attack complexity, requires low privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2026-20849 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (58th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-20849?

CVE-2026-20849 primarily affects Microsoft Windows 10 1607. In total, 19 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2026-20849?

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-2026-20849 have an EU (EUVD) identifier?

Yes. CVE-2026-20849 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-2160.

When was CVE-2026-20849 published?

CVE-2026-20849 was published on 2026-01-13 and last updated on 2026-06-17.

CVE-2026-20849

CVE-2026-20849 is a high-severity vulnerability in Microsoft Windows 10 1607 with a CVSS 3.x base score of 7.5. 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-807.

Key facts

Severity: High (CVSS 3.x base score 7.5)
EPSS exploit prediction: 1% (58th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-2160
Weakness: CWE-807
Affected product: Microsoft Windows 10 1607
Published: 2026-01-13
Last modified: 2026-06-17

Description

Reliance on untrusted inputs in a security decision in Windows Kerberos allows an authorized attacker to elevate privileges over a network.

Frequently asked questions

What is CVE-2026-20849?: Reliance on untrusted inputs in a security decision in Windows Kerberos allows an authorized attacker to elevate privileges over a network.
How severe is CVE-2026-20849?: CVE-2026-20849 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with high attack complexity, requires low privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2026-20849 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (58th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-20849?: CVE-2026-20849 primarily affects Microsoft Windows 10 1607. In total, 19 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2026-20849?: 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-2026-20849 have an EU (EUVD) identifier?: Yes. CVE-2026-20849 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-2160.
When was CVE-2026-20849 published?: CVE-2026-20849 was published on 2026-01-13 and last updated on 2026-06-17.

References

https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-20849

Affected products (19)

cpe:2.3:o:microsoft:windows_10_1607:*:*:*:*:*:*:x64:*
cpe:2.3:o:microsoft:windows_10_1607:*:*:*:*:*:*:x86:*
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_2008:-:sp2:*:*:*:*:x64:*
cpe:2.3:o:microsoft:windows_server_2008:-:sp2:*:*:*:*:x86:*
cpe:2.3:o:microsoft:windows_server_2008:r2:sp1:*:*:*:*:x64:*
cpe:2.3:o:microsoft:windows_server_2012:-:*:*:*:*:*:*:*
cpe:2.3:o:microsoft:windows_server_2012:r2:*:*:*:*:*:*:*
cpe:2.3:o:microsoft:windows_server_2016:*:*:*:*:*:*:*:*
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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