CVE-2019-15271

What are Cisco RV Series Routers?

The Cisco RV320 and RV325 (and related RV-series) are small-business dual-WAN VPN routers widely deployed at branch offices and small businesses for site-to-site VPN and internet gateway functions. Their web-based management interface, while convenient, has been a frequent source of vulnerabilities because it is sometimes left exposed to the internet for remote administration.

Overview

CVE-2019-15271 is a deserialization-of-untrusted-data vulnerability in the web-based management interface of certain Cisco Small Business RV Series routers. An attacker who can reach the management interface and has (or obtains) low-level authenticated access can submit a malicious serialized object that, when deserialized by the device, executes arbitrary code with root privileges on the router's underlying operating system. CVSS 3.1 base score 8.8 (High).

Technical Details

This is CWE-502 (Deserialization of Untrusted Data). The management interface accepts serialized data as part of certain requests without adequately validating its structure or origin before passing it to a deserialization routine. Because the deserialization process runs with root privileges on the embedded Linux-based router firmware, a successfully crafted malicious object can result in full compromise of the device — including firmware modification, traffic interception, and use of the router as a pivot point into the internal network it protects.

Discovery

The vulnerability was identified and patched by Cisco as part of its routine PSIRT vulnerability handling process; Cisco's advisory does not credit a named external researcher for this specific finding.

Exploitation Context

CISA added CVE-2019-15271 to the KEV catalog in June 2022, confirming real-world exploitation. Cisco RV-series routers have historically been popular targets for botnets and nation-state actors alike, since compromising the router provides a durable foothold at the network edge — with visibility into and control over all traffic passing between a small office and the internet.

Remediation

1. Apply the Cisco firmware update that resolves CVE-2019-15271, available through Cisco's software download portal for the affected RV-series models.
2. Disable remote (WAN-side) management access to the router's web interface; restrict administration to the trusted LAN only.
3. Change default credentials and enforce strong, unique passwords for any accounts with management access.
4. If the device has reached end-of-life and no patch is available for your specific model, replace it with a supported device.
5. Monitor router logs and network traffic for signs of unauthorized configuration changes or unusual outbound connections indicating compromise.