Cisco Small Business RV Series Routers Management Interface Remote Command Execution and Denial of Service Vulnerabilities

Vulnerability

Multiple vulnerabilities in the web-based management interface of Cisco Small Business RV016, RV042, RV042G, RV082, RV320, and RV325 Routers (CVE-2021-1337) stem from improper validation of user-supplied input. An authenticated attacker with valid administrator credentials can send crafted HTTP requests to trigger a buffer overflow or other memory corruption, leading to arbitrary code execution or a device reload. These vulnerabilities affect all firmware versions prior to the fixed releases listed in the Cisco advisory [1].

Exploitation

An attacker must have valid administrator credentials for the targeted device. No special network position is required beyond reachability of the web-based management interface (typically LAN or VPN). The attacker sends a series of specially crafted HTTP requests to the vulnerable endpoints. No user interaction from other administrators is needed. The exploitation is a single-step remote attack once authenticated [1].

Impact

Successful exploitation allows the attacker to execute arbitrary code as the root user on the underlying operating system, gaining full control of the device. Alternatively, the attacker can cause the device to reload (denial of service). The CIA impact is complete compromise of confidentiality, integrity, and availability for the affected router [1].

Mitigation

Cisco has released fixed firmware versions. The advisory [1] details the specific fixed releases for each affected model. Users should upgrade immediately. No workarounds are listed; Cisco recommends restricting access to the management interface to trusted IPs and using strong, unique administrator credentials as general security practices. The devices are not listed on the CISA KEV as of the publication date [1].