CVE-2020-17128 [High] | RCE in 365 Apps

CVE-2020-17128 is rated High Risk (67/100): CVSS High severity, with high exploitation likelihood (EPSS 12.66%, 94th percentile). EPSS ranks this CVE among the most likely to be exploited in the near term. EPSS rose +3.01% over the last day, indicating growing attacker interest. High exploitation likelihood—assess exposure and prioritize remediation.

#	Date	Old EPSS score	New EPSS score	Delta (New - Old)
1	2025-11-21	9.65%	12.66%	+3.01%
2	2025-11-18	12.66%	9.65%	-3.01%
3	2025-10-30	—	12.66%	—

Date

Old EPSS score

New EPSS score

Delta (New - Old)

2025-11-21

9.65%

12.66%

+3.01%

2025-11-18

12.66%

9.65%

-3.01%

2025-10-30

—

12.66%

—

Base score	Version	Severity	Vector	Exploitability	Impact	Score source
7.8	3.1	HIGH	`CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H` 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:H) They could widely tamper with or forge data—trust in the data is badly hurt. Availability (A:H) Could take the service down hard or make it unusable for people who depend on it.	1.8	5.9	[email protected]
7.8	3.1	HIGH	`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H` 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:L) A normal user session is enough; they don’t have to be admin. User interaction (UI:N) Nobody has to click “OK” or open a trap file; it can work without a victim helping. 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:H) They could widely tamper with or forge data—trust in the data is badly hurt. Availability (A:H) Could take the service down hard or make it unusable for people who depend on it.	1.8	5.9	[email protected]
9.3	2.0	HIGH	`AV:N/AC:M/Au:N/C:C/I:C/A:C` 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:C) Complete confidentiality impact. Integrity impact (I:C) Complete integrity impact. Availability impact (A:C) Complete availability impact.	8.6	10.0	[email protected]

Base score

Version

Severity

Vector

Exploitability

Impact

Score source

7.8

3.1

HIGH

CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H 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:H): They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:H): Could take the service down hard or make it unusable for people who depend on it.

1.8

5.9

[email protected]

7.8

3.1

HIGH

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H 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:L): A normal user session is enough; they don’t have to be admin.
User interaction (UI:N): Nobody has to click “OK” or open a trap file; it can work without a victim helping.
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:H): They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:H): Could take the service down hard or make it unusable for people who depend on it.

1.8

5.9

[email protected]

9.3

2.0

HIGH

AV:N/AC:M/Au:N/C:C/I:C/A:C 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:C): Complete confidentiality impact.
Integrity impact (I:C): Complete integrity impact.
Availability impact (A:C): Complete availability impact.

8.6

10.0

[email protected]

Affected software / configurations for CVE-2020-17128

Vendor	Product	Version	Raw CPE
microsoft	365_apps	—	cpe:2.3:a:microsoft:365_apps:-::::enterprise:::
microsoft	excel	2010	cpe:2.3:a:microsoft:excel:2010:sp2::::::
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	2010	cpe:2.3:a:microsoft:office:2010:sp2::::::
microsoft	office	2016	cpe:2.3:a:microsoft:office:2016::-::-::-:
microsoft	office	2019	cpe:2.3:a:microsoft:office:2019:::::macos::
microsoft	office_online_server	—	cpe:2.3:a:microsoft:office_online_server:-:::::::*
microsoft	office_web_apps	2013	cpe:2.3:a:microsoft:office_web_apps:2013:sp1::::::

References for CVE-2020-17128

URL	Tags
https://msrc.microsoft.com/update-guide/vulnerability/CVE-2020-17128
https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2020-17128	Patch Vendor Advisory

URL

CVE-2020-17128 | Microsoft Excel Remote Code Execution Vulnerability

Exploit prediction scoring system (EPSS) score for CVE-2020-17128

Common vulnerability scoring system (CVSS) metrics for CVE-2020-17128

Weakness enumeration for CVE-2020-17128

Affected software / configurations for CVE-2020-17128

References for CVE-2020-17128