How severe is CVE-2026-26154?

CVE-2026-26154 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.

Is CVE-2026-26154 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (61st percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-26154?

CVE-2026-26154 primarily affects Microsoft Windows Server 2012. In total, 7 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2026-26154?

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-2026-26154 have an EU (EUVD) identifier?

Yes. CVE-2026-26154 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-22376.

When was CVE-2026-26154 published?

CVE-2026-26154 was published on 2026-04-14 and last updated on 2026-06-17.

CVE-2026-26154

CVE-2026-26154 is a high-severity vulnerability in Microsoft Windows Server 2012 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-20.

Key facts

Severity: High (CVSS 3.x base score 7.5)
EPSS exploit prediction: 1% (61st percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-22376
Weakness: CWE-20
Affected product: Microsoft Windows Server 2012
Published: 2026-04-14
Last modified: 2026-06-17

Description

Improper input validation in Windows Server Update Service allows an unauthorized attacker to perform tampering over a network.

Frequently asked questions

What is CVE-2026-26154?: Improper input validation in Windows Server Update Service allows an unauthorized attacker to perform tampering over a network.
How severe is CVE-2026-26154?: CVE-2026-26154 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.
Is CVE-2026-26154 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (61st percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-26154?: CVE-2026-26154 primarily affects Microsoft Windows Server 2012. In total, 7 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2026-26154?: 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-2026-26154 have an EU (EUVD) identifier?: Yes. CVE-2026-26154 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-22376.
When was CVE-2026-26154 published?: CVE-2026-26154 was published on 2026-04-14 and last updated on 2026-06-17.

References

https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-26154

Affected products (7)

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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