A vulnerability in the TCP packet processing functionality of Cisco IP Phones could allow an unauthenticated, remote attacker to cause the phone to stop responding to incoming calls, drop connected calls, or unexpectedly reload. The vulnerability is due to insufficient TCP ingress packet rate limiting. An attacker could exploit this vulnerability by sending a high and sustained rate of crafted TCP traffic to the targeted device. A successful exploit could allow the attacker to impact operations of the phone or cause the phone to reload, leading to a denial of service (DoS) condition. 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://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-voip-phone-flood-dos-YnU9EXOv
A vulnerability in the TCP packet processing functionality of Cisco IP Phones could allow an unauthenticated, remote attacker to cause the phone to stop responding to incoming calls, drop connected calls, or unexpectedly reload.
The vulnerability is due to insufficient TCP ingress packet rate limiting. An attacker could exploit this vulnerability by sending a high and sustained rate of crafted TCP traffic to the targeted device. A successful exploit could allow the attacker to impact operations of the phone or cause the phone to reload, leading to a denial of service (DoS) condition.
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://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-voip-phone-flood-dos-YnU9EXOv
This vulnerability affects the following Cisco IP Phones if they are running a vulnerable firmware release:
Note: The default configurations of these devices are 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:
Note: The devices listed may see a performance impact from the same attack traffic, but will recover without user intervention once the attack traffic is stopped.
There are no workarounds that address this vulnerability.
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.html
Additionally, 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 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 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.html
Customers 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.
Customers are advised to upgrade to an appropriate fixed firmware release as indicated in the following table:
| Cisco IP Phone Model | Cisco Bug ID | First Fixed Release |
|---|---|---|
| IP DECT 210 Multi-Cell Base Station with Multiplatform Firmware IP DECT 6825 with Multiplatform Firmware |
CSCvt83239 | 4.8.1 |
| IP Phone 8811 Series with Multiplatform Firmware IP Phone 8841 Series with Multiplatform Firmware IP Phone 8851 Series with Multiplatform Firmware IP Phone 8861 Series with Multiplatform Firmware |
CSCvs66815 | 11.3.2 |
| Unified IP Conference Phone 8831 for Third-Party Call Control | CSCvu36012 | There is no fixed firmware available at this time. |
| Webex Room Phone | CSCvu36026 | 1.2.0 |
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.
This vulnerability was found during the resolution of a Cisco TAC support case.
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.
| Version | Description | Section | Status | Date |
|---|---|---|---|---|
| 1.2 | Updated the Fixed Software section to indicate fix released for Webex Room Phone. | Fixed Software | Final | 2021-JAN-19 |
| 1.1 | Updated the Fixed Software section for the Webex Room Phone. | Fixed Software | Final | 2020-DEC-22 |
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