high
7.4
CWE
670
Advisory Published
Updated

CVE-2021-34767: Cisco IOS XE Software for Catalyst 9800 Series Wireless Controllers IPv6 Denial of Service Vulnerability

First published: Thu Sep 23 2021(Updated: )

A vulnerability in IPv6 traffic processing of Cisco IOS XE Wireless Controller Software for Cisco Catalyst 9000 Family Wireless Controllers could allow an unauthenticated, adjacent attacker to cause a Layer 2 (L2) loop in a configured VLAN, resulting in a denial of service (DoS) condition for that VLAN. The vulnerability is due to a logic error when processing specific link-local IPv6 traffic. An attacker could exploit this vulnerability by sending a crafted IPv6 packet that would flow inbound through the wired interface of an affected device. A successful exploit could allow the attacker to cause traffic drops in the affected VLAN, thus triggering the DoS condition.

Credit: ykramarz@cisco.com

Affected SoftwareAffected VersionHow to fix
Cisco IOS XE
Cisco IOS XE=3.15.1xbs
Cisco IOS XE=3.15.2xbs
Cisco IOS XE=16.7.1
Cisco IOS XE=16.7.1a
Cisco IOS XE=16.7.1b
Cisco IOS XE=16.7.2
Cisco IOS XE=16.7.3
Cisco IOS XE=16.7.4
Cisco IOS XE=16.8.1
Cisco IOS XE=16.8.1a
Cisco IOS XE=16.8.1b
Cisco IOS XE=16.8.1c
Cisco IOS XE=16.8.1d
Cisco IOS XE=16.8.1e
Cisco IOS XE=16.8.1s
Cisco IOS XE=16.8.2
Cisco IOS XE=16.8.3
Cisco IOS XE=16.9.1
Cisco IOS XE=16.9.1a
Cisco IOS XE=16.9.1b
Cisco IOS XE=16.9.1c
Cisco IOS XE=16.9.1d
Cisco IOS XE=16.9.1s
Cisco IOS XE=16.9.2
Cisco IOS XE=16.9.2a
Cisco IOS XE=16.9.2s
Cisco IOS XE=16.9.3
Cisco IOS XE=16.9.3a
Cisco IOS XE=16.9.3h
Cisco IOS XE=16.9.3s
Cisco IOS XE=16.9.4
Cisco IOS XE=16.9.4c
Cisco IOS XE=16.9.5
Cisco IOS XE=16.9.5f
Cisco IOS XE=16.9.6
Cisco IOS XE=16.9.7
Cisco IOS XE=16.10.1
Cisco IOS XE=16.10.1a
Cisco IOS XE=16.10.1b
Cisco IOS XE=16.10.1c
Cisco IOS XE=16.10.1d
Cisco IOS XE=16.10.1e
Cisco IOS XE=16.10.1f
Cisco IOS XE=16.10.1g
Cisco IOS XE=16.10.1s
Cisco IOS XE=16.10.2
Cisco IOS XE=16.10.3
Cisco IOS XE=16.11.1
Cisco IOS XE=16.11.1a
Cisco IOS XE=16.11.1b
Cisco IOS XE=16.11.1c
Cisco IOS XE=16.11.1s
Cisco IOS XE=16.11.2
Cisco IOS XE=16.12.1
Cisco IOS XE=16.12.1a
Cisco IOS XE=16.12.1c
Cisco IOS XE=16.12.1s
Cisco IOS XE=16.12.1t
Cisco IOS XE=16.12.1w
Cisco IOS XE=16.12.1x
Cisco IOS XE=16.12.1y
Cisco IOS XE=16.12.1z
Cisco IOS XE=16.12.1z1
Cisco IOS XE=16.12.1za
Cisco IOS XE=16.12.2
Cisco IOS XE=16.12.2a
Cisco IOS XE=16.12.2s
Cisco IOS XE=16.12.2t
Cisco IOS XE=16.12.3
Cisco IOS XE=16.12.3a
Cisco IOS XE=16.12.3s
Cisco IOS XE=16.12.4
Cisco IOS XE=16.12.4a
Cisco IOS XE=17.1.1
Cisco IOS XE=17.1.1a
Cisco IOS XE=17.1.1s
Cisco IOS XE=17.1.1t
Cisco IOS XE=17.1.2
Cisco IOS XE=17.1.3
Cisco IOS XE=17.2.1
Cisco IOS XE=17.2.1a
Cisco IOS XE=17.2.1r
Cisco IOS XE=17.2.1v
Cisco IOS XE=17.2.2
Cisco IOS XE=17.2.3
Cisco IOS XE=17.3.1
Cisco IOS XE=17.3.1a
Cisco IOS XE=17.3.1w
Cisco IOS XE=17.3.1x
Cisco IOS XE=17.3.1z
Cisco IOS XE=17.3.2
Cisco IOS XE=17.3.2a
Cisco Catalyst 9800 Firmware
Cisco Catalyst 9800-40
Cisco Catalyst 9800-80
Cisco Catalyst 9800-L
Cisco Catalyst 9800-L firmware
Cisco Catalyst 9800-L
Cisco Catalyst 9800-L
Cisco Catalyst 9800 Embedded Wireless Controller

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Reference Links

Frequently Asked Questions

  • What is the severity of CVE-2021-34767?

    CVE-2021-34767 has a CVSS score indicating a critical severity level due to the potential for Denial of Service.

  • How do I fix CVE-2021-34767?

    To fix CVE-2021-34767, you should upgrade your Cisco IOS XE software to the latest patched version provided by Cisco.

  • What impact does CVE-2021-34767 have on affected systems?

    CVE-2021-34767 can lead to a Layer 2 loop within a VLAN, resulting in service interruption or Denial of Service.

  • Which Cisco devices are affected by CVE-2021-34767?

    CVE-2021-34767 affects various versions of Cisco IOS XE running on Catalyst 9000 Family Wireless Controllers.

  • Can an attacker exploit CVE-2021-34767 remotely?

    No, CVE-2021-34767 requires an unauthenticated, adjacent attacker to exploit the vulnerability.

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