What is CVE-2020-16955?

An elevation of privilege vulnerability exists in the way that Microsoft Office Click-to-Run (C2R) AppVLP handles certain files. An attacker who successfully exploited the vulnerability could elevate privileges. To exploit this vulnerability, an attacker would need to convince a user to open a specially crafted file. The security update addresses the vulnerability by correcting how Microsoft Office Click-to-Run (C2R) components handle these files.

How severe is CVE-2020-16955?

CVE-2020-16955 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-2020-16955 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 3% (87th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2020-16955?

CVE-2020-16955 primarily affects Microsoft 365 Apps. In total, 3 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2020-16955?

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-2020-16955 published?

CVE-2020-16955 was published on 2020-10-16 and last updated on 2026-06-17.

CVE-2020-16955

CVE-2020-16955 is a high-severity vulnerability in Microsoft 365 Apps 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.

Key facts

Severity: High (CVSS 3.x base score 7.8)
CVSS v2: 6.8
EPSS exploit prediction: 3% (87th percentile)
Actively exploited: Not listed in CISA KEV
Affected product: Microsoft 365 Apps
Published: 2020-10-16
Last modified: 2026-06-17

Description

An elevation of privilege vulnerability exists in the way that Microsoft Office Click-to-Run (C2R) AppVLP handles certain files. An attacker who successfully exploited the vulnerability could elevate privileges. To exploit this vulnerability, an attacker would need to convince a user to open a specially crafted file. The security update addresses the vulnerability by correcting how Microsoft Office Click-to-Run (C2R) components handle these files.

Frequently asked questions

What is CVE-2020-16955?: An elevation of privilege vulnerability exists in the way that Microsoft Office Click-to-Run (C2R) AppVLP handles certain files. An attacker who successfully exploited the vulnerability could elevate privileges. To exploit this vulnerability, an attacker would need to convince a user to open a specially crafted file. The security update addresses the vulnerability by correcting how Microsoft Office Click-to-Run (C2R) components handle these files.
How severe is CVE-2020-16955?: CVE-2020-16955 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-2020-16955 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 3% (87th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2020-16955?: CVE-2020-16955 primarily affects Microsoft 365 Apps. In total, 3 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2020-16955?: 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-2020-16955 published?: CVE-2020-16955 was published on 2020-10-16 and last updated on 2026-06-17.

References

https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2020-16955

Affected products (3)

cpe:2.3:a:microsoft:365_apps:-:*:*:*:enterprise:*:*:*
cpe:2.3:a:microsoft:office:2013:*:*:*:click-to-run:*:*:*
cpe:2.3:a:microsoft:office:2019:*:*:*:*:-:*:*

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