medium
4.3
CWE
20
Advisory Published
Updated

CVE-2021-1220: Cisco IOS XE Software Web UI Denial of Service Vulnerabilities

First published: Wed Mar 24 2021(Updated: )

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.

Credit: ykramarz@cisco.com

Affected SoftwareAffected VersionHow to fix
Cisco IOS XE Web UI=3.15.1xbs
Cisco IOS XE Web UI=3.15.2xbs
Cisco IOS XE Web UI=16.11.1
Cisco IOS XE Web UI=16.11.1a
Cisco IOS XE Web UI=16.11.1b
Cisco IOS XE Web UI=16.11.1c
Cisco IOS XE Web UI=16.11.1s
Cisco IOS XE Web UI=16.11.2
Cisco IOS XE Web UI=16.12.1
Cisco IOS XE Web UI=16.12.1a
Cisco IOS XE Web UI=16.12.1c
Cisco IOS XE Web UI=16.12.1s
Cisco IOS XE Web UI=16.12.1t
Cisco IOS XE Web UI=16.12.1w
Cisco IOS XE Web UI=16.12.1x
Cisco IOS XE Web UI=16.12.1y
Cisco IOS XE Web UI=16.12.1z
Cisco IOS XE Web UI=16.12.2
Cisco IOS XE Web UI=16.12.2a
Cisco IOS XE Web UI=16.12.2s
Cisco IOS XE Web UI=16.12.2t
Cisco IOS XE Web UI=16.12.3
Cisco IOS XE Web UI=16.12.3a
Cisco IOS XE Web UI=16.12.3s
Cisco IOS XE Web UI=16.12.4
Cisco IOS XE Web UI=16.12.4a
Cisco IOS XE Web UI=17.1.1
Cisco IOS XE Web UI=17.1.1a
Cisco IOS XE Web UI=17.1.1s
Cisco IOS XE Web UI=17.1.1t
Cisco IOS XE Web UI=17.1.2
Cisco IOS XE Web UI=17.2.1
Cisco IOS XE Web UI=17.2.1a
Cisco IOS XE Web UI=17.2.1r
Cisco IOS XE Web UI=17.2.1v
Cisco IOS XE Web UI

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Reference Links

Frequently Asked Questions

  • What is the severity of CVE-2021-1220?

    CVE-2021-1220 is classified as a denial of service (DoS) vulnerability.

  • What software versions are affected by CVE-2021-1220?

    CVE-2021-1220 affects multiple versions of Cisco IOS XE Software.

  • How do I fix CVE-2021-1220?

    To fix CVE-2021-1220, administrators should apply the latest security patches provided by Cisco.

  • What type of attack does CVE-2021-1220 enable?

    CVE-2021-1220 enables an authenticated remote attacker to perform a denial of service attack on the web UI.

  • What impact does CVE-2021-1220 have on systems?

    CVE-2021-1220 can cause the web UI to become unresponsive and exhaust vty line instances.

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