CVE-2023-20215 [Medium] | Security Bypass in Asyncos

A vulnerability in the scanning engines of Cisco AsyncOS Software for Cisco Secure Web Appliance could allow an unauthenticated, remote attacker to bypass a configured rule, allowing traffic onto a network that should have been blocked. This vulnerability is due to improper detection of malicious traffic when the traffic is encoded with a specific content format. An attacker could exploit this vulnerability by using an affected device to connect to a malicious server and receiving crafted HTTP responses. A successful exploit could allow the attacker to bypass an explicit block rule and receive traffic that should have been rejected by the device.

#	Date	Old EPSS score	New EPSS score	Delta (New - Old)
1	2025-03-19	0.02%	0.07%	+0.04%
2	2025-03-17	0.05%	0.02%	-0.03%
3	2023-08-12	—	0.05%	—

Date

Old EPSS score

New EPSS score

Delta (New - Old)

2025-03-19

0.02%

0.07%

+0.04%

2025-03-17

0.05%

0.02%

-0.03%

2023-08-12

—

0.05%

—

Base score	Version	Severity	Vector	Exploitability	Impact	Score source
5.8	3.1	MEDIUM	`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:N` 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: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:L) Attackers could change some data, but it’s limited—not everything goes. Availability (A:N) Service keeps running; no real outage angle.	3.9	1.4	[email protected]
5.3	3.1	MEDIUM	`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N` 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: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:L) Attackers could change some data, but it’s limited—not everything goes. Availability (A:N) Service keeps running; no real outage angle.	3.9	1.4	[email protected]

Base score

Version

Severity

Vector

Exploitability

Impact

Score source

5.8

3.1

MEDIUM

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:N 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: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:L): Attackers could change some data, but it’s limited—not everything goes.
Availability (A:N): Service keeps running; no real outage angle.

3.9

1.4

[email protected]

5.3

3.1

MEDIUM

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N 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: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:L): Attackers could change some data, but it’s limited—not everything goes.
Availability (A:N): Service keeps running; no real outage angle.

3.9

1.4

[email protected]

Affected software / configurations for CVE-2023-20215

Vendor	Product	Version	Raw CPE
cisco	asyncos	11.7.0-406	cpe:2.3:o:cisco:asyncos:11.7.0-406:::::::*
cisco	asyncos	11.7.0-418	cpe:2.3:o:cisco:asyncos:11.7.0-418:::::::*
cisco	asyncos	11.7.1-006	cpe:2.3:o:cisco:asyncos:11.7.1-006:::::::*
cisco	asyncos	11.7.1-020	cpe:2.3:o:cisco:asyncos:11.7.1-020:::::::*
cisco	asyncos	11.7.1-049	cpe:2.3:o:cisco:asyncos:11.7.1-049:::::::*
cisco	asyncos	11.7.2-011	cpe:2.3:o:cisco:asyncos:11.7.2-011:::::::*
cisco	asyncos	11.8.0-414	cpe:2.3:o:cisco:asyncos:11.8.0-414:::::::*
cisco	asyncos	11.8.1-023	cpe:2.3:o:cisco:asyncos:11.8.1-023:::::::*
cisco	asyncos	11.8.3-018	cpe:2.3:o:cisco:asyncos:11.8.3-018:::::::*
cisco	asyncos	11.8.3-021	cpe:2.3:o:cisco:asyncos:11.8.3-021:::::::*
cisco	asyncos	12.0.1-268	cpe:2.3:o:cisco:asyncos:12.0.1-268:::::::*
cisco	asyncos	12.0.3-007	cpe:2.3:o:cisco:asyncos:12.0.3-007:::::::*
cisco	asyncos	12.5.1-011	cpe:2.3:o:cisco:asyncos:12.5.1-011:::::::*
cisco	asyncos	12.5.2-007	cpe:2.3:o:cisco:asyncos:12.5.2-007:::::::*
cisco	asyncos	12.5.4-005	cpe:2.3:o:cisco:asyncos:12.5.4-005:::::::*
cisco	asyncos	12.5.5-004	cpe:2.3:o:cisco:asyncos:12.5.5-004:::::::*
cisco	asyncos	14.0.2-012	cpe:2.3:o:cisco:asyncos:14.0.2-012:::::::*
cisco	asyncos	14.0.3-014	cpe:2.3:o:cisco:asyncos:14.0.3-014:::::::*
cisco	asyncos	14.0.4-005	cpe:2.3:o:cisco:asyncos:14.0.4-005:::::::*
cisco	asyncos	14.5.0-498	cpe:2.3:o:cisco:asyncos:14.5.0-498:::::::*
cisco	asyncos	14.5.1-008	cpe:2.3:o:cisco:asyncos:14.5.1-008:::::::*
cisco	asyncos	14.5.1-016	cpe:2.3:o:cisco:asyncos:14.5.1-016:::::::*

References for CVE-2023-20215

URL	Tags
https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-wsa-bypass-vXvqwzsj	Vendor Advisory

URL

CVE-2023-20215

Exploit prediction scoring system (EPSS) score for CVE-2023-20215

Common vulnerability scoring system (CVSS) metrics for CVE-2023-20215

Weakness enumeration for CVE-2023-20215

Affected software / configurations for CVE-2023-20215

References for CVE-2023-20215