CVE-2021-34791 Security feature bypass in Cisco Adaptive Security Appliance (ASA) Software

Medium 4.7 Published 27 Oct 2021 Updated 7 Nov 2024

Unauthenticated remote attackers can bypass the Application Level Gateway to open unauthorized connections to hosts behind the firewall.

Exploited in the wild: Not known
Login needed: Not needed
Attackable: Over the internet
Victim action needed: A user has to click or open something
Fix: None listed

What is CVE-2021-34791?

CVE-2021-34791 is a medium-severity vulnerability in Cisco Adaptive Security Appliance, published on 27 Oct 2021. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.

Official description

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.

Weakness: CWE-20, CWE-358

Which versions are affected by CVE-2021-34791?

It affects 11 products.

Products include Cisco Adaptive Security Appliance, Cisco Adaptive Security Appliance Software, Cisco Asa 5505 Firmware, Cisco Asa 5512-X Firmware, Cisco Asa 5515-X Firmware, Cisco Asa 5525-X Firmware and 5 more.

How do I fix CVE-2021-34791?

No fix has been published for CVE-2021-34791 yet. Limit exposure of the affected software until one is available.

Is CVE-2021-34791 being exploited?

There is no known exploitation of CVE-2021-34791 in the wild and no public exploit code.

All Cisco Adaptive Security Appliance vulnerabilities

Sources

Also known as GHSA-qhq7-rm64-qh84.