CVE-2021-34790 json
Cisco Adaptive Security Appliance Software and Firepower Threat Defense Software Application Level Gateway Bypass Vulnerabilities
published 2021-10-27 5 y ago modified 2026-08-11 2 mo ago also EUVD-2021-21440
- cvss
- 4.7
- version 3.1, CNA
- cisa kev
- Not listed
- not in CISA's catalog
- epss
- 1.1%
- EPSS 1.1% chance of exploitation in 30 days, percentile 66%
- public exploits
- 0
- none known
Summary
Multiple 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.
Patch / fix
- cisco adaptive_security_appliance 9.8.4.40
- cisco secure_firewall_threat_defense 6.4.0.12, 6.6.5, 6.7.0.2
- cisco adaptive_security_appliance_software 9.12.4.29, 9.14.2.15, 9.15.1.15
CISA SSVC
- Exploitation
- none
- Automatable
- no
- Technical impact
- partial
- Assessed
- 2 y ago
Exploit prediction
1.15% chance of exploitation in the next 30 days, higher than 66% of all scored CVEs (FIRST EPSS, 2026-11-08).
CVSS scores
| assigned by | version | score | vector |
|---|---|---|---|
| CNA | 3.1 | 4.7 | CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:N/I:L/A:N |
| NVD | 3.1 | 5.3 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N |
| NVD | 2.0 | 5.0 | AV:N/AC:L/Au:N/C:N/I:P/A:N |
Affected products
- Cisco Cisco Adaptive Security Appliance (ASA) Software
Classification
References
Sources
- CVE List CVE-2021-34790
- NVD CVE-2021-34790
Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.