How severe is CVE-2026-63520?

CVE-2026-63520 has a CVSS 3.x base score of 8.1, rated high severity. It is exploitable over network with high attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2026-63520 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (68th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-63520?

CVE-2026-63520 primarily affects Microsoft Sharepoint Server. In total, 3 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2026-63520?

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.

When was CVE-2026-63520 published?

CVE-2026-63520 was published on 2026-08-11 and last updated on 2026-08-13.

CVE-2026-63520

CVE-2026-63520 is a high-severity vulnerability in Microsoft Sharepoint Server with a CVSS 3.x base score of 8.1. 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 8.1)
EPSS exploit prediction: 1% (68th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-20
Affected product: Microsoft Sharepoint Server
Published: 2026-08-11
Last modified: 2026-08-13

Description

Improper input validation in Microsoft Office SharePoint allows an unauthorized attacker to execute code over a network.

Frequently asked questions

What is CVE-2026-63520?: Improper input validation in Microsoft Office SharePoint allows an unauthorized attacker to execute code over a network.
How severe is CVE-2026-63520?: CVE-2026-63520 has a CVSS 3.x base score of 8.1, rated high severity. It is exploitable over network with high attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2026-63520 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (68th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-63520?: CVE-2026-63520 primarily affects Microsoft Sharepoint Server. In total, 3 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2026-63520?: 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.
When was CVE-2026-63520 published?: CVE-2026-63520 was published on 2026-08-11 and last updated on 2026-08-13.

References

https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-63520

Affected products (3)

cpe:2.3:a:microsoft:sharepoint_server:*:*:*:*:subscription:*:*:*
cpe:2.3:a:microsoft:sharepoint_server:2016:*:*:*:enterprise:*:*:*
cpe:2.3:a:microsoft:sharepoint_server:2019:*:*:*:*:*:*:*

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