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CVE-2021-34787
CVE-2021-34787
Description
A vulnerability in the identity-based firewall (IDFW) rule processing feature of Cisco Adaptive Security Appliance (ASA) Software and Cisco Firepower Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to bypass security protections. This vulnerability is due to improper handling of network requests by affected devices configured to use object group search. An attacker could exploit this vulnerability by sending a specially crafted network request to an affected device. A successful exploit could allow the attacker to bypass access control list (ACL) rules on the device, bypass security protections, and send network traffic to unauthorized hosts.
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Technical Analysis
I’m not super clear yet on why Cisco rates this as “Medium” severity. A remote, unauthenticated ACL bypass in a network edge product seems like a fairly high-severity bug, though admittedly it doesn’t appear to be RCE, which I guess is something. I can’t imagine it’ll take long for PoCs to show up—we’ll see.
Exploitability sounds high from an initial read, but I’ll reserve official judgment on that until we see what the exploit dev community comes up with.
Edit: @jbaines-r7 makes the excellent point that if this turns out to be blind, it’s of significantly less value to an attacker.
CVSS V3 Severity and Metrics
General Information
Vendors
- Cisco
Products
- Cisco Adaptive Security Appliance (ASA) Software
References
