CVE-2022-20708

What is Cisco Small Business RV Series?

The Cisco Small Business RV160, RV260, RV340, and RV345 series are VPN routers for small and medium businesses, commonly deployed at network edges with internet-facing web management interfaces for remote administration.

Overview

CVE-2022-20708 is a command injection vulnerability in the web-based management interface of Cisco Small Business RV series routers, rated CVSS 10.0. While classified with CWE-121 (stack-based buffer overflow) in NVD, the practical impact described in the Cisco advisory includes the ability to execute arbitrary OS commands on the router. An unauthenticated attacker who can reach the management interface can inject shell commands that execute with root privileges. This is the fifth CVE in Cisco's February 2022 advisory batch for the RV router family.

Affected Versions

Technical Details

CVE-2022-20708 involves insufficient validation of input data passed to the web management server, which is used to configure the router's features. The management interface passes user-supplied values to underlying shell commands without proper sanitization, allowing an attacker to append arbitrary OS commands via injection characters (e.g., ;, |, $(...)).

The CVSS 10.0 score reflects:

• No authentication required — the injection point is accessible before login
• Network-accessible attack surface (management port is internet-facing in many deployments)
• Changed scope — OS-level access from a web tier vulnerability
• Full CIA impact on the device

Discovery

Reported by Quentin Kaiser of IoT Inspector Research Lab as part of the same audit that uncovered the four companion CVEs in this advisory.

Exploitation Context

OS command injection is often simpler to exploit than stack buffer overflows — no return-oriented programming or shellcode is required. An attacker simply appends shell metacharacters to an input field and observes the result. This makes CVE-2022-20708 particularly accessible to lower-sophistication threat actors, even compared to the other RV router CVEs in the same advisory.

The five CVEs in this Cisco advisory (20699, 20700, 20701, 20703, 20708) collectively represent one of the broadest attack surface disclosures for a single SMB router product in 2022. Organizations with unpatched RV series devices faced complete perimeter compromise from any of five independently exploitable paths.

Remediation

1. Update firmware: Install 1.0.01.05 (RV160/RV260) or 1.0.03.24 (RV340/RV345) via the device admin console.
2. Disable remote web management: If remote administration is not required, disable the management interface from WAN-facing access.
3. IP allowlist: Restrict management access to known administrator IP addresses only.
4. Replace end-of-support models: Apply to all models in the RV160/260/340/345 family simultaneously.
5. Verify firmware version: After updating, confirm the running firmware version via the status page to ensure the update applied successfully.