CVE-2020-3509 Cisco IOS XE Software for Cisco cBR-8 Converged Broadband Routers DHCP Denial of Service Vulnerability
Remote unauthenticated attackers can crash Cisco cBR-8 routers by sending malicious DHCPv4 messages, causing a denial of service.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2020-3509?
CVE-2020-3509 is a high-severity denial of service vulnerability in Cisco Ios Xe, published on 24 Sep 2020. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
A vulnerability in the DHCP message handler of Cisco IOS XE Software for Cisco cBR-8 Converged Broadband Routers could allow an unauthenticated, remote attacker to cause the supervisor to crash, which could result in a denial of service (DoS) condition. The vulnerability is due to insufficient error handling when DHCP version 4 (DHCPv4) messages are parsed. An attacker could exploit this vulnerability by sending a malicious DHCPv4 message to or through a WAN interface of an affected device. A successful exploit could allow the attacker to cause a reload of the affected device. Note: On Cisco cBR-8 Converged Broadband Routers, all of the following are considered WAN interfaces: 10 Gbps Ethernet interfaces 100 Gbps Ethernet interfaces Port channel interfaces that include multiple 10 and/or 100 Gbps Ethernet interfaces
Which versions are affected by CVE-2020-3509?
It affects 1 product.
Products include Cisco Ios Xe.
How do I fix CVE-2020-3509?
No fix has been published for CVE-2020-3509 yet. Limit exposure of the affected software until one is available.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2020-3509 being exploited?
There is no known exploitation of CVE-2020-3509 in the wild and no public exploit code.
Other vulnerabilities in Cisco Ios Xe
- CVE-2023-20198 Cisco IOS XE Web UI Privilege Escalation
- CVE-2018-0151 Cisco IOS Software and Cisco IOS XE Software Quality of Service Remote Code Execution
- CVE-2023-20273 Cisco IOS XE Web UI Command Injection
- CVE-2025-20188 Hardcoded credentials in Cisco IOS XE Software
- CVE-2021-34770 Cisco IOS XE Software for Catalyst 9000 Family Wireless Controllers CAPWAP Remote Code Execution Vulnerability
Sources
Also known as GHSA-w99f-f6h3-qccc.