A vulnerability in the nginx configurations that are provided as part of the VPN-less reverse proxy for Cisco Finesse could allow an unauthenticated, remote attacker to create a denial of service (DoS) condition for new and existing users who are connected through a load balancer.
This vulnerability is due to improper IP address filtering by the reverse proxy. An attacker could exploit this vulnerability by sending a series of unauthenticated requests to the reverse proxy. A successful exploit could allow the attacker to cause all current traffic and subsequent requests to the reverse proxy through a load balancer to be dropped, resulting in a DoS condition.
Cisco has released software updates that address this vulnerability. There are workarounds that address this vulnerability.
This advisory is available at the following link:
At the time of publication, this vulnerability affected Cisco Finesse only if the reverse proxy was installed and requests to the reverse proxy were routed through the load balancer.
The following Cisco products, which may be bundled with Cisco Finesse, were also affected by this vulnerability:
- Packaged Contact Center Enterprise (PCCE)
- Unified Contact Center Enterprise (UCCE)
- Unified Contact Center Express (UCCX)
For information about which Cisco software releases were vulnerable at the time of publication, see the Fixed Software section of this advisory. See the Details section in the bug ID(s) at the top of this advisory for the most complete and current information.
Products Confirmed Not Vulnerable
Only products listed in the Vulnerable Products section of this advisory are known to be affected by this vulnerability.
A workaround for this vulnerability is available for customers who cannot upgrade to a fixed release. To coordinate implementation of the workaround, contact the Cisco Technical Assistance Center (TAC).
While this workaround 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.
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.
At the time of publication, the release information in the following table was accurate. See the Details section in the bug ID(s) at the top of this advisory for the most complete and current information.
The left column lists Cisco software releases, and the right column indicates whether a release was affected by the vulnerability that is described in this advisory and which release included the fix for this vulnerability.
Cisco Finesse Release First Fixed Release Earlier than 12.6(1) ES7 12.6(1) ES7
In addition to installing the fixed release, the following configurations must be applied to the reverse proxy and on any intermediary devices such as load balancers:
- Intermediary network devices that are front-ending the reverse proxy, such as load balancers, should be exempted from configurations that are meant for rate limiting and blocking unauthorized access to avoid blocking the reverse proxy IP address instead of the unauthorized user IP addresses. To configure these devices correctly, follow Step 1 in the Cisco Unified Contact Center Enterprise Features Guide, Release 12.6(1) - Reverse-Proxy Configuration.
- Intermediary network devices that are front-ending the reverse proxy, such as load balancers, should be enabled with the capability to allow requests to contain the user IP addresses instead of the IP addresses of the intermediary devices. To configure these devices correctly, follow Steps 2 and 3 in the Cisco Unified Contact Center Enterprise Features Guide, Release 12.6(1) - Reverse-Proxy Configuration.
The Cisco Product Security Incident Response Team (PSIRT) validates only the affected and fixed release information that is documented in this advisory.
The Cisco 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 1.1 Clarified which releases are vulnerable. Fixed Releases Final 2023-MAR-02 1.0 Initial public release. — Final 2023-MAR-01
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