Cisco Adaptive Security Appliance and Cisco Firepower Threat Defense Software AnyConnect SSL VPN Denial of Service Vulnerability

Summary

CVE	CVE-2022-20795
State	PUBLISHED
Assigner	cisco
Source Priority	CVE Program / NVD first with legacy fallback
Published	2022-04-21 19:15:08 UTC
Updated	2026-08-11 19:37:30 UTC
Description	A vulnerability in the implementation of the Datagram TLS (DTLS) protocol in Cisco Adaptive Security Appliance (ASA) Software and Cisco Firepower Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to cause high CPU utilization, resulting in a denial of service (DoS) condition. This vulnerability is due to suboptimal processing that occurs when establishing a DTLS tunnel as part of an AnyConnect SSL VPN connection. An attacker could exploit this vulnerability by sending a steady stream of crafted DTLS traffic to an affected device. A successful exploit could allow the attacker to exhaust resources on the affected VPN headend device. This could cause existing DTLS tunnels to stop passing traffic and prevent new DTLS tunnels from establishing, resulting in a DoS condition. Note: When the attack traffic stops, the device recovers gracefully.

Risk And Classification

Primary CVSS: v3.1 7.5 HIGH from [email protected]

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

EPSS: 0.006850000 probability, percentile 0.493770000 (date 2026-08-12)

Problem Types: CWE-345 | CWE-345 CWE-345

Version	Source	Type	Score	Severity	Vector
3.1	[email protected]	Primary	7.5	HIGH	`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H`
3.1	[email protected]	Secondary	5.8	MEDIUM	`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:L`
3.1	CNA	DECLARED	5.8	MEDIUM	`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:L`
2.0	[email protected]	Primary	5		`AV:N/AC:L/Au:N/C:N/I:N/A:P`

CVSS v3.1 Breakdown

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

None

Scope

Unchanged

Confidentiality

None

Integrity

None

Availability

High

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

CVSS v2.0 Breakdown

Access Vector

Network

Access Complexity

Low

Authentication

None

Confidentiality

None

Integrity

None

Availability

Partial

AV:N/AC:L/Au:N/C:N/I:N/A:P

NVD Known Affected Configurations (CPE 2.3)

Type	Vendor	Product	Version	Update	Edition	Language
Application	Cisco	Adaptive Security Appliance	All	All	All	All
Operating System	Cisco	Adaptive Security Appliance Software	All	All	All	All
Hardware	Cisco	Asa 5505	-	All	All	All
Hardware	Cisco	Asa 5512-x	-	All	All	All
Hardware	Cisco	Asa 5515-x	-	All	All	All
Hardware	Cisco	Asa 5525-x	-	All	All	All
Hardware	Cisco	Asa 5545-x	-	All	All	All
Hardware	Cisco	Asa 5555-x	-	All	All	All
Hardware	Cisco	Asa 5580	-	All	All	All
Hardware	Cisco	Asa 5585-x	-	All	All	All
Hardware	Cisco	Asa For Nexus 1000v	-	All	All	All
Hardware	Cisco	Firepower 1010	-	All	All	All
Hardware	Cisco	Firepower 1120	-	All	All	All
Hardware	Cisco	Firepower 1140	-	All	All	All
Hardware	Cisco	Firepower 1150	-	All	All	All
Hardware	Cisco	Firepower 2110	-	All	All	All
Hardware	Cisco	Firepower 2120	-	All	All	All
Hardware	Cisco	Firepower 2130	-	All	All	All
Hardware	Cisco	Firepower 2140	-	All	All	All
Hardware	Cisco	Firepower 4110	-	All	All	All
Hardware	Cisco	Firepower 4112	-	All	All	All
Hardware	Cisco	Firepower 4115	-	All	All	All
Hardware	Cisco	Firepower 4120	-	All	All	All
Hardware	Cisco	Firepower 4125	-	All	All	All
Hardware	Cisco	Firepower 4140	-	All	All	All
Hardware	Cisco	Firepower 4145	-	All	All	All
Hardware	Cisco	Firepower 4150	-	All	All	All
Hardware	Cisco	Firepower 9300	-	All	All	All
Application	Cisco	Secure Firewall Threat Defense	All	All	All	All
Application	Cisco	Secure Firewall Threat Defense	All	All	All	All

Vendor Declared Affected Products

Source	Vendor	Product	Version	Platforms
CNA	Cisco	Cisco Adaptive Security Appliance ASA Software	affected n/a	Not specified

References

Reference	Source	Link	Tags
tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-vpndtl...	af854a3a-2127-422b-91ae-364da2661108	tools.cisco.com	Vendor Advisory
CVE Program record	CVE.ORG	www.cve.org	canonical
NVD vulnerability detail	NVD	nvd.nist.gov	canonical, analysis

No vendor comments have been submitted for this CVE.

Additional Advisory Data

Exploits

CNA: The Cisco Product Security Incident Response Team (PSIRT) is aware that proof-of-concept exploit code is available for the vulnerability described in this advisory.

Legacy QID Mappings

317160 Cisco Adaptive Security Appliance (ASA) AnyConnect Secure Sockets Layer (SSL) Virtual Private Network (VPN) Denial of Service (DoS) Vulnerability (cisco-sa-vpndtls-dos-TunzLEV)
317161 Cisco Firepower Threat Defense (FTD) Software AnyConnect Secure Sockets Layer (SSL) Virtual Private Network (VPN) Denial of Service (DoS) Vulnerability (cisco-sa-vpndtls-dos-TunzLEV)