CVE-2020-3132 [Medium] | Denial of Service in Cloud Email Security

A vulnerability in the email message scanning feature of Cisco AsyncOS Software for Cisco Email Security Appliance (ESA) could allow an unauthenticated, remote attacker to cause a temporary denial of service (DoS) condition on an affected device. The vulnerability is due to inadequate parsing mechanisms for specific email body components. An attacker could exploit this vulnerability by sending a malicious email containing a high number of shortened URLs through an affected device. A successful exploit could allow the attacker to consume processing resources, causing a DoS condition on an affected device. To successfully exploit this vulnerability, certain conditions beyond the control of the attacker must occur.

#	Date	Old EPSS score	New EPSS score	Delta (New - Old)
1	2026-06-15	0.92%	1.47%	+0.55%
2	2025-11-21	0.40%	0.92%	+0.52%
3	2025-11-18	—	0.40%	—

Date

Old EPSS score

New EPSS score

Delta (New - Old)

2026-06-15

0.92%

1.47%

+0.55%

2025-11-21

0.40%

0.92%

+0.52%

2025-11-18

—

0.40%

—

Base score	Version	Severity	Vector	Exploitability	Impact	Score source
5.9	3.1	MEDIUM	`CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/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:H) Even with access, the exploit needs extra luck, timing, or a fussy environment to actually work. Privileges required (PR:N) No account or special rights needed—anonymous or random user is enough. 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:N) Doesn’t really leak secrets in a meaningful way. Integrity (I:N) Data isn’t meaningfully altered or forged. Availability (A:H) Could take the service down hard or make it unusable for people who depend on it.	2.2	3.6	[email protected]
6.8	3.0	MEDIUM	`CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:N/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:H) Even with access, the exploit needs extra luck, timing, or a fussy environment to actually work. Privileges required (PR:N) No account or special rights needed—anonymous or random user is enough. User interaction (UI:N) Nobody has to click “OK” or open a trap file; it can work without a victim helping. Scope (S:C) Breaking this can reach past the original component and bite other resources—bigger blast radius. Confidentiality (C:N) Doesn’t really leak secrets in a meaningful way. Integrity (I:N) Data isn’t meaningfully altered or forged. Availability (A:H) Could take the service down hard or make it unusable for people who depend on it.	2.2	4.0	[email protected]
7.1	2.0	HIGH	`AV:N/AC:M/Au:N/C:N/I:N/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:N) No confidentiality impact. Integrity impact (I:N) No integrity impact. Availability impact (A:C) Complete availability impact.	8.6	6.9	[email protected]

Base score

Version

Severity

Vector

Exploitability

Impact

Score source

5.9

3.1

MEDIUM

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/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:H): Even with access, the exploit needs extra luck, timing, or a fussy environment to actually work.
Privileges required (PR:N): No account or special rights needed—anonymous or random user is enough.
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:N): Doesn’t really leak secrets in a meaningful way.
Integrity (I:N): Data isn’t meaningfully altered or forged.
Availability (A:H): Could take the service down hard or make it unusable for people who depend on it.

2.2

3.6

[email protected]

6.8

3.0

MEDIUM

CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:N/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:H): Even with access, the exploit needs extra luck, timing, or a fussy environment to actually work.
Privileges required (PR:N): No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N): Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:C): Breaking this can reach past the original component and bite other resources—bigger blast radius.
Confidentiality (C:N): Doesn’t really leak secrets in a meaningful way.
Integrity (I:N): Data isn’t meaningfully altered or forged.
Availability (A:H): Could take the service down hard or make it unusable for people who depend on it.

2.2

4.0

[email protected]

7.1

2.0

HIGH

AV:N/AC:M/Au:N/C:N/I:N/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:N): No confidentiality impact.
Integrity impact (I:N): No integrity impact.
Availability impact (A:C): Complete availability impact.

8.6

6.9

[email protected]

Affected software / configurations for CVE-2020-3132

Vendor	Product	Version	Raw CPE
cisco	cloud_email_security	< 12.5.1-037	cpe:2.3:a:cisco:cloud_email_security::::::::
cisco	email_security_appliance	< 12.5.1-037	cpe:2.3:a:cisco:email_security_appliance::::::::
cisco	cloud_email_security	< 13.0.0-375	cpe:2.3:a:cisco:cloud_email_security::::::::
cisco	email_security_appliance	< 13.0.0-375	cpe:2.3:a:cisco:email_security_appliance::::::::

References for CVE-2020-3132

URL	Tags
https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-esa-shrt-dos-wM54R8qA	Vendor Advisory

URL

CVE-2020-3132 | Cisco Email Security Appliance Shortened URL Denial of Service Vulnerability

Exploit prediction scoring system (EPSS) score for CVE-2020-3132

Common vulnerability scoring system (CVSS) metrics for CVE-2020-3132

Weakness enumeration for CVE-2020-3132

Affected software / configurations for CVE-2020-3132

References for CVE-2020-3132