CVE-2021-31178 | Microsoft Office Information Disclosure Vulnerability

Microsoft Office Information Disclosure Vulnerability

Published: 2021-05-11 Last update: 2026-06-16 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2021-31178 is rated Moderate Risk (50.8/100): CVSS Medium severity, with high exploitation likelihood (EPSS 16.01%, 96th percentile). EPSS ranks this CVE among the most likely to be exploited in the near term. High exploitation likelihood—assess exposure and prioritize remediation.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2021-31178

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-06-15 28.37% 16.01% -12.36%
2 2026-06-01 33.13% 28.37% -4.76%
3 2026-05-31 — 33.13% —

Full EPSS history (41 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2021-31178

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
5.5 3.1 MEDIUM
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N Click to expand
Attack vector (AV:L)
They already need access on the box, or another person has to do something wrong; it’s not a remote drive-by.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:R)
A real person has to do something—click, install, enable—otherwise it doesn’t land.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:N)
Service keeps running; no real outage angle.
 1.8 3.6 [email protected]
5.5 3.1 MEDIUM
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N Click to expand
Attack vector (AV:L)
They already need access on the box, or another person has to do something wrong; it’s not a remote drive-by.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:R)
A real person has to do something—click, install, enable—otherwise it doesn’t land.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:N)
Service keeps running; no real outage angle.
 1.8 3.6 [email protected]
4.3 2.0 MEDIUM
AV:N/AC:M/Au:N/C:P/I:N/A:N Click to expand
Access vector (AV:N)
Can be exploited remotely over network reachability.
Access complexity (AC:M)
Exploitation needs some favorable conditions, but not exceptional ones.
Authentication (AU:N)
No authentication is required.
Confidentiality impact (C:P)
Partial confidentiality impact.
Integrity impact (I:N)
No integrity impact.
Availability impact (A:N)
No availability impact.
 8.6 2.9 [email protected]

Weakness enumeration for CVE-2021-31178

Affected software / configurations for CVE-2021-31178

Vendor Product Version Raw CPE
microsoft 365_apps — cpe:2.3:a:microsoft:365_apps:-:*:*:*:enterprise:*:*:*
microsoft excel 2013 cpe:2.3:a:microsoft:excel:2013:sp1:*:*:*:*:*:*
microsoft excel 2013 cpe:2.3:a:microsoft:excel:2013:sp1:*:*:rt:*:*:*
microsoft excel 2016 cpe:2.3:a:microsoft:excel:2016:*:*:*:*:*:*:*
microsoft office 2013 cpe:2.3:a:microsoft:office:2013:sp1:*:*:*:*:*:*
microsoft office 2013 cpe:2.3:a:microsoft:office:2013:sp1:*:*:rt:*:*:*
microsoft office 2016 cpe:2.3:a:microsoft:office:2016:*:*:*:*:-:*:*
microsoft office 2019 cpe:2.3:a:microsoft:office:2019:*:*:*:*:-:*:*
microsoft office_online_server — cpe:2.3:a:microsoft:office_online_server:-:*:*:*:*:*:*:*
microsoft office_web_apps_server 2013 cpe:2.3:a:microsoft:office_web_apps_server:2013:sp1:*:*:*:*:*:*
microsoft word 2013 cpe:2.3:a:microsoft:word:2013:sp1:*:*:*:*:*:*
microsoft word 2013 cpe:2.3:a:microsoft:word:2013:sp1:*:*:rt:*:*:*
microsoft word 2016 cpe:2.3:a:microsoft:word:2016:*:*:*:*:*:*:*

References for CVE-2021-31178

cvelogic Threat Intelligence