CVE-2021-1220 Cisco IOS XE Software Web UI Denial of Service Vulnerabilities
Authenticated remote attackers can cause denial of service in Cisco IOS XE web UI by sending crafted HTTP packets, requiring manual intervention to restore.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2021-1220?
CVE-2021-1220 is a medium-severity denial of service vulnerability in Cisco Ios Xe, published on 24 Mar 2021. Any signed-in user can exploit it over the network, with no action from the victim.
Official description
Multiple vulnerabilities in the web UI of Cisco IOS XE Software could allow an authenticated, remote attacker with read-only privileges to cause the web UI software to become unresponsive and consume vty line instances, resulting in a denial of service (DoS) condition. These vulnerabilities are due to insufficient error handling in the web UI. An attacker could exploit these vulnerabilities by sending crafted HTTP packets to an affected device. A successful exploit could allow the attacker to cause the web UI software to become unresponsive and consume all available vty lines, preventing new session establishment and resulting in a DoS condition. Manual intervention would be required to regain web UI and vty session functionality. Note: These vulnerabilities do not affect the console connection.
Weakness: CWE-20
Which versions are affected by CVE-2021-1220?
It affects 1 product.
Products include Cisco Ios Xe.
How do I fix CVE-2021-1220?
No fix has been published for CVE-2021-1220 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-2021-1220 being exploited?
There is no known exploitation of CVE-2021-1220 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-4m9r-j9f4-4m4g.