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Cisco IOS XE Software Layer 2 Tunneling Protocol Denial of Service Vulnerability

cisco-sa-ios-xe-l2tp-dos-eB5tuFmV · High · Published · Updated

A vulnerability in the Layer 2 Tunneling Protocol (L2TP) feature of Cisco IOS XE Software could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on an affected device. This vulnerability is due to improper handling of certain L2TP packets. An attacker could exploit this vulnerability by sending crafted L2TP packets to an affected device. A successful exploit could allow the attacker to cause the device to reload unexpectedly, resulting in a DoS condition. Note: Only traffic directed to the affected system can be used to exploit this vulnerability. Cisco has released software updates that address this vulnerability. There are no workarounds that address this vulnerability. This advisory is available at the following link:https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-ios-xe-l2tp-dos-eB5tuFmV This advisory is part of the September 2023 release of the Cisco IOS and IOS XE Software Security Advisory Bundled Publication. For a complete list of the advisories and links to them, see Cisco Event Response: September 2023 Semiannual Cisco IOS and IOS XE Software Security Advisory Bundled Publication.

Cisco advisory · CSAF JSON

Workarounds

There are no workarounds that address this vulnerability.

However, to reduce the attack surface, administrators may apply infrastructure access control lists (iACLs) to block UDP port 1701 on interfaces where L2TP packets are not expected to be received. The following is an iACL example that can be included as part of the deployed iACL:

Router# show ip access-lists CVE-2023-20227
10 deny udp any INFRASTRUCTURE_ADDRESSES WILDCARD eq 1701
20 permit ip any any
Router#

For more guidelines and recommendations for deployment techniques for iACLs, see the white paper Protecting Your Core: Infrastructure Protection Access Control Lists ["https://www.cisco.com/c/en/us/support/docs/ip/access-lists/43920-iacl.html"].

While this mitigation has been deployed and was proven successful in a test environment, customers should determine the applicability and effectiveness in their own environment and under their own use conditions. Customers should be aware that any workaround or mitigation that is implemented may negatively impact the functionality or performance of their network based on intrinsic customer deployment scenarios and limitations. Customers should not deploy any workarounds or mitigations before first evaluating the applicability to their own environment and any impact to such environment.

CVEsCVE-2023-20227
Cisco Bug IDsCSCwe70596
CVSS ScoreBase 8.6
Base 8.6 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H/E:X/RL:X/RC:X
Product Names From Source
Cisco IOS XE Software 16.8.1, Cisco IOS XE Software 16.8.1a, Cisco IOS XE Software 16.8.1b, Cisco IOS XE Software 16.8.1s, Cisco IOS XE Software 16.8.1c, Cisco IOS XE Software 16.8.1d, Cisco IOS XE Software 16.8.2, Cisco IOS XE Software 16.8.1e, Cisco IOS XE Software 16.8.3, Cisco IOS XE Software 16.9.1, Cisco IOS XE Software 16.9.2, Cisco IOS XE Software 16.9.1a, Cisco IOS XE Software 16.9.1b, Cisco IOS XE Software 16.9.1s, Cisco IOS XE Software 16.9.1c, Cisco IOS XE Software 16.9.3, Cisco IOS XE Software 16.9.2a, Cisco IOS XE Software 16.9.2s, Cisco IOS XE Software 16.9.3h, Cisco IOS XE Software 16.9.4, Cisco IOS XE Software 16.9.3s, Cisco IOS XE Software 16.9.4c, Cisco IOS XE Software 16.9.5, Cisco IOS XE Software 16.9.5f, Cisco IOS XE Software 16.9.6, Cisco IOS XE Software 16.9.7, Cisco IOS XE Software 16.9.8, Cisco IOS XE Software 16.9.8a, Cisco IOS XE Software 16.9.8b, Cisco IOS XE Software 16.10.1, Cisco IOS XE Software 16.10.1a, Cisco IOS XE Software 16.10.1b, Cisco IOS XE Software 16.10.1s, Cisco IOS XE Software 16.10.1c, Cisco IOS XE Software 16.10.1e, Cisco IOS XE Software 16.10.1d, Cisco IOS XE Software 16.10.2, Cisco IOS XE Software 16.10.1f, Cisco IOS XE Software 16.10.1g, Cisco IOS XE Software 16.10.3, Cisco IOS XE Software 16.11.1, Cisco IOS XE Software 16.11.1a, Cisco IOS XE Software 16.11.1b, Cisco IOS XE Software 16.11.2, Cisco IOS XE Software 16.11.1s, Cisco IOS XE Software 16.11.1c, Cisco IOS XE Software 16.12.1, Cisco IOS XE Software 16.12.1s, Cisco IOS XE Software 16.12.1a, Cisco IOS XE Software 16.12.1c, Cisco IOS XE Software 16.12.1w, Cisco IOS XE Software 16.12.2, Cisco IOS XE Software 16.12.1y, Cisco IOS XE Software 16.12.2a, Cisco IOS XE Software 16.12.3, Cisco IOS XE Software 16.12.8, Cisco IOS XE Software 16.12.2s, Cisco IOS XE Software 16.12.1x, Cisco IOS XE Software 16.12.1t, Cisco IOS XE Software 16.12.2t, Cisco IOS XE Software 16.12.4, Cisco IOS XE Software 16.12.3s, Cisco IOS XE Software 16.12.1z, Cisco IOS XE Software 16.12.4a, Cisco IOS XE Software 16.12.5, Cisco IOS XE Software 16.12.6, Cisco IOS XE Software 16.12.1z1, Cisco IOS XE Software 16.12.5a, Cisco IOS XE Software 16.12.1z2, Cisco IOS XE Software 16.12.6a, Cisco IOS XE Software 16.12.7, Cisco IOS XE Software 16.12.10a, Cisco IOS XE Software 17.1.1, Cisco IOS XE Software 17.1.1a, Cisco IOS XE Software 17.1.1s, Cisco IOS XE Software 17.1.2, Cisco IOS XE Software 17.1.1t, Cisco IOS XE Software 17.1.3, Cisco IOS XE Software 17.2.1, Cisco IOS XE Software 17.2.1r, Cisco IOS XE Software 17.2.1a, Cisco IOS XE Software 17.2.1v, Cisco IOS XE Software 17.2.2, Cisco IOS XE Software 17.2.3, Cisco IOS XE Software 17.3.1, Cisco IOS XE Software 17.3.2, Cisco IOS XE Software 17.3.3, Cisco IOS XE Software 17.3.1a, Cisco IOS XE Software 17.3.1w, Cisco IOS XE Software 17.3.2a, Cisco IOS XE Software 17.3.1x, Cisco IOS XE Software 17.3.1z, Cisco IOS XE Software 17.3.4, Cisco IOS XE Software 17.3.5, Cisco IOS XE Software 17.3.4a, Cisco IOS XE Software 17.3.6, Cisco IOS XE Software 17.3.4c, Cisco IOS XE Software 17.3.5a, Cisco IOS XE Software 17.3.5b, Cisco IOS XE Software 17.3.7, Cisco IOS XE Software 17.4.1, Cisco IOS XE Software 17.4.2, Cisco IOS XE Software 17.4.1a, Cisco IOS XE Software 17.4.1b, Cisco IOS XE Software 17.4.2a, Cisco IOS XE Software 17.5.1, Cisco IOS XE Software 17.5.1a, Cisco IOS XE Software 17.5.1b, Cisco IOS XE Software 17.5.1c, Cisco IOS XE Software

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