Vulnerability identifier: #VU57767

Vulnerability risk: Medium

CVSSv3.1: 5.1 [CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:N/E:U/RL:O/RC:C]

CVE-ID: CVE-2021-34787

CWE-ID: CWE-264

Exploitation vector: Network

Exploit availability: No

Vulnerable software:
ASA 5500-X Series Firewalls
Other software / Other software solutions
Cisco Adaptive Security Appliance (ASA)
Hardware solutions / Security hardware applicances
Cisco Firepower Threat Defense (FTD)
Hardware solutions / Security hardware applicances

Vendor: Cisco Systems, Inc

Description

The vulnerability allows a remote attacker to bypass implemented security restrictions.

The vulnerability exists in the identity-based firewall (IDFW) rule processing feature. A remote attacker can send a specially crafted network request to bypass access control list (ACL) rules on the device, bypass security protections, and send network traffic to unauthorized hosts.

Mitigation
Install updates from vendor's website.

Vulnerable software versions

ASA 5500-X Series Firewalls: All versions

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External links
http://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-asaftd-rule-bypass-ejjOgQEY
http://bst.cloudapps.cisco.com/bugsearch/bug/CSCvx47895

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Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the Internet.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability.