Cisco Adaptive Security Appliance Software and Firepower Threat Defense Software Application Level Gateway Bypass Vulnerabilities

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Summary

CVECVE-2021-34790
StatePUBLISHED
Assignercisco
Source PriorityCVE Program / NVD first with legacy fallback
Published2021-10-27 19:15:08 UTC
Updated2026-08-11 19:37:30 UTC
DescriptionMultiple vulnerabilities in the Application Level Gateway (ALG) for the Network Address Translation (NAT) feature of Cisco Adaptive Security Appliance (ASA) Software and Firepower Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to bypass the ALG and open unauthorized connections with a host located behind the ALG. For more information about these vulnerabilities, see the Details section of this advisory. Note: These vulnerabilities have been publicly discussed as NAT Slipstreaming.

Risk And Classification

Primary CVSS: v3.1 5.3 MEDIUM from [email protected]

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

Problem Types: CWE-358 | CWE-20 | CWE-358 CWE-358

VersionSourceTypeScoreSeverityVector
3.1[email protected]Primary5.3MEDIUMCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
3.1[email protected]Secondary4.7MEDIUMCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:N/I:L/A:N
3.1CNADECLARED4.7MEDIUMCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:N/I:L/A:N
2.0[email protected]Primary5AV:N/AC:L/Au:N/C:N/I:P/A:N

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
Low
Availability
None

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

CVSS v2.0 Breakdown

Access Vector
Network
Access Complexity
Low
Authentication
None
Confidentiality
None
Integrity
Partial
Availability
None

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

NVD Known Affected Configurations (CPE 2.3)

TypeVendorProductVersionUpdateEditionLanguage
Application Cisco Adaptive Security Appliance All All All All
Application Cisco Secure Firewall Threat Defense All All All All

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Cisco Cisco Adaptive Security Appliance ASA Software affected n/a Not specified

References

ReferenceSourceLinkTags
Cisco Adaptive Security Appliance Software and Firepower Threat Defense Software Application Level Gateway Bypass Vulnerabilities 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

Additional Advisory Data

Exploits

CNA: The Cisco PSIRT is aware that proof-of-concept exploit code is available for the vulnerabilities described in this advisory.

Legacy QID Mappings

  • 317094 Cisco Adaptive Security Appliance (ASA) Software Application Level Gateway v Bypass Vulnerabilities (cisco-sa-natalg-bypass-cpKGqkng)
  • 317096 Cisco Firepower Threat Defense (FTD) Software Application Level Gateway (ALG) Bypass Vulnerabilities (cisco-sa-natalg-bypass-cpKGqkng)

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