CVE-2020-0688 [Exploited] | Microsoft EXCHANGE SERVER Authentication Bypass

CVE-2020-0688 is rated Critical Active Threat (95.4/100): CVSS High severity, with high exploitation likelihood (EPSS 94.40%, 100th percentile). CISA KEV confirms active exploitation (added 2021-11-03) affecting Microsoft / Exchange Server. an authentication bypass (CWE-287) Unauthenticated remote administrative access may be possible. The CISA remediation deadline has passed—treat as an emergency patch priority.

EDB-ID	Source	Kind	Published	Link
48168	exploit_db	edb	2020-03-05	Exploit-DB ↗
48153	exploit_db	edb	2020-03-02	Exploit-DB ↗
—	nvd_ref	exploit_tag		Exploit-DB ↗
—	nvd_ref	exploit_tag		Exploit-DB ↗

EDB-ID

Source

Kind

Published

Link

48168

exploit_db

edb

2020-03-05

Exploit-DB ↗

48153

exploit_db

edb

2020-03-02

Exploit-DB ↗

—

nvd_ref

exploit_tag

Exploit-DB ↗

—

nvd_ref

exploit_tag

Exploit-DB ↗

#	Date	Old EPSS score	New EPSS score	Delta (New - Old)
1	2025-11-21	94.19%	94.40%	+0.22%
2	2025-11-18	94.42%	94.19%	-0.23%
3	2025-06-27	—	94.42%	—

Date

Old EPSS score

New EPSS score

Delta (New - Old)

2025-11-21

94.19%

94.40%

+0.22%

2025-11-18

94.42%

94.19%

-0.23%

2025-06-27

—

94.42%

—

Base score	Version	Severity	Vector	Exploitability	Impact	Score source
8.8	3.1	HIGH	`CVSS:3.1/AV:N/AC:L/PR:L/UI:N/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: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.	2.8	5.9	[email protected]
8.8	3.1	HIGH	`CVSS:3.1/AV:N/AC:L/PR:L/UI:N/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: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.	2.8	5.9	134c704f-9b21-4f2e-91b3-4a467353bcc0
9.0	2.0	HIGH	`AV:N/AC:L/Au:S/C:C/I:C/A:C` Click to expand Access vector (AV:N) Can be exploited remotely over network reachability. Access complexity (AC:L) Exploitation conditions are straightforward and predictable. Authentication (AU:S) A single authentication is required. Confidentiality impact (C:C) Complete confidentiality impact. Integrity impact (I:C) Complete integrity impact. Availability impact (A:C) Complete availability impact.	8.0	10.0	[email protected]

Base score

Version

Severity

Vector

Exploitability

Impact

Score source

8.8

3.1

HIGH

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/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: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.

2.8

5.9

[email protected]

8.8

3.1

HIGH

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/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: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.

2.8

5.9

134c704f-9b21-4f2e-91b3-4a467353bcc0

9.0

2.0

HIGH

AV:N/AC:L/Au:S/C:C/I:C/A:C Click to expand

Access vector (AV:N): Can be exploited remotely over network reachability.
Access complexity (AC:L): Exploitation conditions are straightforward and predictable.
Authentication (AU:S): A single authentication is required.
Confidentiality impact (C:C): Complete confidentiality impact.
Integrity impact (I:C): Complete integrity impact.
Availability impact (A:C): Complete availability impact.

8.0

10.0

[email protected]

Affected software / configurations for CVE-2020-0688

Vendor	Product	Version	Raw CPE
microsoft	exchange_server	2010	cpe:2.3:a:microsoft:exchange_server:2010:sp3_rollup_30::::::
microsoft	exchange_server	2013	cpe:2.3:a:microsoft:exchange_server:2013:cumulative_update_23::::::
microsoft	exchange_server	2016	cpe:2.3:a:microsoft:exchange_server:2016:cumulative_update_14::::::
microsoft	exchange_server	2016	cpe:2.3:a:microsoft:exchange_server:2016:cumulative_update_15::::::
microsoft	exchange_server	2019	cpe:2.3:a:microsoft:exchange_server:2019:cumulative_update_3::::::
microsoft	exchange_server	2019	cpe:2.3:a:microsoft:exchange_server:2019:cumulative_update_4::::::

References for CVE-2020-0688

URL	Tags
http://packetstormsecurity.com/files/156592/Microsoft-Exchange-2019-15.2.221.12-Remote-Code-Execution.html	Exploit Third Party Advisory VDB Entry
http://packetstormsecurity.com/files/156620/Exchange-Control-Panel-Viewstate-Deserialization.html	Exploit Third Party Advisory VDB Entry
https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2020-0688	Patch Vendor Advisory
https://www.zerodayinitiative.com/advisories/ZDI-20-258/	Third Party Advisory VDB Entry
https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2020-0688	US Government Resource

URL

CVE-2020-0688

CISA KEV Record for CVE-2020-0688

Public exploit references (Exploit-DB) for CVE-2020-0688

Exploit prediction scoring system (EPSS) score for CVE-2020-0688

Common vulnerability scoring system (CVSS) metrics for CVE-2020-0688

Weakness enumeration for CVE-2020-0688

Affected software / configurations for CVE-2020-0688

References for CVE-2020-0688