CVE-2021-34535 [High] | RCE in Remote Desktop Client

CVE-2021-34535 is rated High Risk (74.1/100): CVSS High severity, with high exploitation likelihood (EPSS 18.35%, 97th percentile). EPSS ranks this CVE among the most likely to be exploited in the near term. EPSS rose +9.13% 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	2026-06-15	9.22%	18.35%	+9.13%
2	2026-05-12	4.76%	9.22%	+4.46%
3	2026-01-03	—	4.76%	—

Date

Old EPSS score

New EPSS score

Delta (New - Old)

2026-06-15

9.22%

18.35%

+9.13%

2026-05-12

4.76%

9.22%

+4.46%

2026-01-03

—

4.76%

—

Base score	Version	Severity	Vector	Exploitability	Impact	Score source
8.8	3.1	HIGH	`CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H` Click to expand Attack vector (AV:N) Could be attacked over the internet or any normal routed network—not just someone sitting at the machine. 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.	2.8	5.9	[email protected]
8.8	3.1	HIGH	`CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H` Click to expand Attack vector (AV:N) Could be attacked over the internet or any normal routed network—not just someone sitting at the machine. 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.	2.8	5.9	[email protected]
6.8	2.0	MEDIUM	`AV:N/AC:M/Au:N/C:P/I:P/A:P` 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:P) Partial integrity impact. Availability impact (A:P) Partial availability impact.	8.6	6.4	[email protected]

Base score

Version

Severity

Vector

Exploitability

Impact

Score source

8.8

3.1

HIGH

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H Click to expand

Attack vector (AV:N): Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
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.

2.8

5.9

[email protected]

8.8

3.1

HIGH

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H Click to expand

Attack vector (AV:N): Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
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.

2.8

5.9

[email protected]

6.8

2.0

MEDIUM

AV:N/AC:M/Au:N/C:P/I:P/A:P 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:P): Partial integrity impact.
Availability impact (A:P): Partial availability impact.

8.6

6.4

[email protected]

Affected software / configurations for CVE-2021-34535

Vendor	Product	Version	Raw CPE
microsoft	remote_desktop_client	—	cpe:2.3:a:microsoft:remote_desktop_client:-:::::windows::
microsoft	windows_10	—	cpe:2.3:o:microsoft:windows_10:-:::::::*
microsoft	windows_10	20h2	cpe:2.3:o:microsoft:windows_10:20h2:::::::*
microsoft	windows_10	21h1	cpe:2.3:o:microsoft:windows_10:21h1:::::::*
microsoft	windows_10	1607	cpe:2.3:o:microsoft:windows_10:1607:::::::*
microsoft	windows_10	1809	cpe:2.3:o:microsoft:windows_10:1809:::::::*
microsoft	windows_10	1909	cpe:2.3:o:microsoft:windows_10:1909:::::::*
microsoft	windows_10	2004	cpe:2.3:o:microsoft:windows_10:2004:::::::*
microsoft	windows_7	—	cpe:2.3:o:microsoft:windows_7:-:sp1::::::
microsoft	windows_8.1	—	cpe:2.3:o:microsoft:windows_8.1:-:::::::*
microsoft	windows_rt_8.1	—	cpe:2.3:o:microsoft:windows_rt_8.1:-:::::::*
microsoft	windows_server_2008	r2	cpe:2.3:o:microsoft:windows_server_2008:r2:sp1:::::x64:*
microsoft	windows_server_2012	—	cpe:2.3:o:microsoft:windows_server_2012:-:::::::*
microsoft	windows_server_2012	r2	cpe:2.3:o:microsoft:windows_server_2012:r2:::::::*
microsoft	windows_server_2016	—	cpe:2.3:o:microsoft:windows_server_2016:-:::::::*
microsoft	windows_server_2019	—	cpe:2.3:o:microsoft:windows_server_2019:-:::::::*

References for CVE-2021-34535

URL	Tags
https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-34535	Patch Vendor Advisory

URL

CVE-2021-34535 | Remote Desktop Client Remote Code Execution Vulnerability

Exploit prediction scoring system (EPSS) score for CVE-2021-34535

Common vulnerability scoring system (CVSS) metrics for CVE-2021-34535

Weakness enumeration for CVE-2021-34535

Affected software / configurations for CVE-2021-34535

References for CVE-2021-34535