Cisco Security Advisory
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CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H/E:X/RL:X/RC:X
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A vulnerability in the Point-to-Point Tunneling Protocol (PPTP) VPN packet processing functionality in Cisco Aironet Access Points (APs) could allow an unauthenticated, remote attacker to cause an affected device to reload, resulting in a denial of service (DoS) condition.
The vulnerability is due to insufficient validation of Generic Routing Encapsulation (GRE) frames that pass through the data plane of an affected AP. An attacker could exploit this vulnerability by associating to a vulnerable AP, initiating a PPTP VPN connection to an arbitrary PPTP VPN server, and sending a malicious GRE frame through the data plane of the AP. A successful exploit could allow the attacker to cause an internal process of the targeted AP to crash, which in turn would cause the AP to reload. The AP reload would cause a DoS condition for clients that are associated with the AP.
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-20191016-airo-pptp-dos
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Vulnerable Products
This vulnerability affects the following Cisco products if they are running a vulnerable software release:
- Aironet 1810 Series APs
- Aironet 1830 Series APs
- Aironet 1850 Series APs
For information about which software releases are vulnerable, see the Fixed Software section of this advisory.
Products Confirmed Not Vulnerable
Only products listed in the Vulnerable Products section of this advisory are known to be affected by this vulnerability.
Cisco has confirmed that this vulnerability does not affect the following Cisco products:
- Aironet 1540 Series APs
- Aironet 1560 Series APs
- Aironet 1800 Series APs not listed in the Vulnerable Products section of this advisory
- Aironet 2800 Series APs
- Aironet 3800 Series APs
- Aironet 4800 APs
- Catalyst 9100 APs
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This vulnerability is a reintroduction of CVE-2018-0234.
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There are no workarounds that address this vulnerability.
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Cisco has released free software updates that address the vulnerability described in this advisory. Customers may only install and expect support for software versions and feature sets for which they have purchased a license. By installing, downloading, accessing, or otherwise using such software upgrades, customers agree to follow the terms of the Cisco software license:
https://www.cisco.com/c/en/us/products/end-user-license-agreement.htmlAdditionally, customers may only download software for which they have a valid license, procured from Cisco directly, or through a Cisco authorized reseller or partner. In most cases this will be a maintenance upgrade to software that was previously purchased. Free security software updates do not entitle customers to a new software license, additional software feature sets, or major revision upgrades.
When considering software upgrades, customers are advised to regularly consult the advisories for Cisco products, which are available from the Cisco Security Advisories and Alerts page, to determine exposure and a complete upgrade solution.
In all cases, customers should ensure that the devices to be upgraded contain sufficient memory and confirm that current hardware and software configurations will continue to be supported properly by the new release. If the information is not clear, customers are advised to contact the Cisco Technical Assistance Center (TAC) or their contracted maintenance providers.
Customers Without Service Contracts
Customers who purchase directly from Cisco but do not hold a Cisco service contract and customers who make purchases through third-party vendors but are unsuccessful in obtaining fixed software through their point of sale should obtain upgrades by contacting the Cisco TAC:
https://www.cisco.com/c/en/us/support/web/tsd-cisco-worldwide-contacts.htmlCustomers should have the product serial number available and be prepared to provide the URL of this advisory as evidence of entitlement to a free upgrade.
Fixed Releases
Customers are advised to upgrade to an appropriate release as indicated in the table in this section. To help ensure a complete upgrade solution, consider that this advisory is part of a collection that includes the following advisories:
- cisco-sa-20191016-airo-capwap-dos: Cisco Aironet Access Points and Catalyst 9100 Access Points CAPWAP Denial of Service Vulnerability
- cisco-sa-20191016-airo-pptp-dos: Cisco Aironet Access Points Point-to-Point Tunneling Protocol Denial of Service Vulnerability
- cisco-sa-20191016-airo-unauth-access: Cisco Aironet Access Points Unauthorized Access Vulnerability
- cisco-sa-20191016-wlc-ssh-dos: Cisco Wireless LAN Controller Secure Shell Denial of Service Vulnerability
In the following table, the left column lists Cisco software releases. The center column indicates whether a release is affected by the vulnerability described in this advisory and the first release that includes the fix for this vulnerability. The right column indicates whether a release is affected by all the vulnerabilities described in this collection of advisories and which release includes fixes for those vulnerabilities.
1. For Release 8.5, releases 8.5.110.0 and later, but earlier than 8.5.140.0, are not vulnerable.Cisco Aironet AP Software Major Release First Fixed Release for This Vulnerability
Recommended Release for All Vulnerabilities Described in the Collection of Advisories Earlier than 8.0
Not vulnerable 8.5.151.0
8.0 Not vulnerable 8.5.151.0
8.1 Not vulnerable 8.5.151.0 8.2 Not vulnerable 8.5.151.0 8.3 Not vulnerable 8.5.151.0 8.4 8.5.151.01 8.5.151.0 8.5 8.5.151.01 8.5.151.0 8.6 Not vulnerable 8.8.125.0 8.7 Not vulnerable 8.8.125.0 8.8 8.8.125.02 8.8.125.0 8.9 8.9.111.0
8.9.111.0 8.10 Not vulnerable
Not vulnerable
2. For Release 8.8, releases earlier than 8.8.111.0 are not vulnerable.
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The Cisco Product Security Incident Response Team (PSIRT) is not aware of any public announcements or malicious use of the vulnerability that is described in this advisory.
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This vulnerability was found during the resolution of a Cisco TAC support case.
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To learn about Cisco security vulnerability disclosure policies and publications, see the Security Vulnerability Policy. This document also contains instructions for obtaining fixed software and receiving security vulnerability information from Cisco.
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Show LessVersion Description Section Status Date 1.0 Initial public release. — Final 2019-October-16
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