How to Fix CVE-2019-1652: input validation in Cisco Small Business RV Series Router Firmware

WARNING: This vulnerability is on the CISA Known Exploited Vulnerabilities catalog (added 2022-03-03). Federal civilian agencies must remediate by 2022-03-17. Treat it as active exploitation, not theoretical.

What is CVE-2019-1652?

A vulnerability in the web-based management interface of Cisco Small Business RV320 and RV325 Dual Gigabit WAN VPN Routers could allow an authenticated, remote attacker with administrative privileges on an affected device to execute arbitrary commands. The vulnerability is due to improper validation of user-supplied input. An attacker could exploit this vulnerability by sending malicious HTTP POST requests to the web-based management interface of an affected device. A successful exploit could allow the attacker to execute arbitrary commands on the underlying Linux shell as root.

What you'll see

From the device CLI, run the version check:

# Cisco IOS/IOS XE
show version | include Version

# FortiGate (FortiOS)
get system status

# Palo Alto (PAN-OS)
show system info | match sw-version

# Juniper (Junos)
show version

Compare what you see against the Affected row above (Cisco). If your build sits inside that range, the device is exposed and should be upgraded.

How to fix CVE-2019-1652

The primary fix is to upgrade Cisco Small Business RV Series Router Firmware to the patched build. Use the commands for your platform below; the patched version listed in the vendor advisory is: See vendor advisory.

Cisco IOS / IOS XE

# Vendor advisory: https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20190123-rv-inject
enable
show version | include Version
copy running-config startup-config
copy tftp: flash:
! upload the patched image, then:
boot system flash:<patched-image>.bin
reload

Complete operator runbook (network appliance)

Run this from your management workstation (Linux/macOS or Windows with a TFTP server reachable). It shells into the device, backs up the running config, transfers the patched image, and reloads.

# Vendor advisory: https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20190123-rv-inject
#!/usr/bin/env bash
# CVE-2019-1652 fix runbook for Cisco Cisco Small Business RV Series Router Firmware
# Target build: the patched build

set -euo pipefail
DEVICE="${1:?usage: $0 <device-ip> <patched-image-file> <tftp-server-ip>}"
IMAGE="${2:?patched image filename required}"
TFTP="${3:?tftp server ip required}"
LOG="/var/log/cve-2019-1652-$(date +%Y%m%d-%H%M%S).log"

echo "[1/4] Pulling current config from $DEVICE"
ssh admin@"$DEVICE" "show version" | tee -a "$LOG"
ssh admin@"$DEVICE" "copy running-config tftp://$TFTP/cve-2019-1652-pre.cfg"

echo "[2/4] Uploading patched image $IMAGE via TFTP"
ssh admin@"$DEVICE" "copy tftp://$TFTP/$IMAGE flash:$IMAGE" | tee -a "$LOG"

echo "[3/4] Setting boot image and reloading"
ssh admin@"$DEVICE" "configure terminal
 boot system flash:$IMAGE
 end
 write memory
 reload" | tee -a "$LOG"

echo "[4/4] Wait ~5 minutes, then verify"
sleep 300
ssh admin@"$DEVICE" "show version | include Version" | tee -a "$LOG"
echo "Compare reported version against the patched build"

If you can't patch immediately

If you cannot apply the patched version today, restrict exposure with one of the following runnable controls. None replace the patch.

Network appliance ACL

# Cisco IOS example: restrict management plane to a trusted subnet
configure terminal
access-list 99 permit 10.0.0.0 0.255.255.255
line vty 0 15
 access-class 99 in
end
write memory

Service-level fallback

# If the affected feature is optional, stop the service until the patch is applied
sudo systemctl stop cisco
sudo systemctl disable cisco

The repair

# Linux
cisco --version 2>/dev/null || dpkg -s cisco | grep -i version
rpm -q cisco 2>/dev/null || true

# Windows
winget list | findstr /I "cisco"
Get-HotFix | Sort-Object InstalledOn -Descending | Select-Object -First 5

Expected: the reported version is at or above the patched build documented in the advisory. Restart any services that loaded the old library (systemctl restart <service> on Linux, restart the Windows service or reboot when prompted). For network appliances, run show version on the device and confirm the build matches the patched release.

Is CVE-2019-1652 actually being exploited?

According to the data sources above, yes, CISA has it listed as actively exploited. Either way, the fix is the same: apply the vendor patch.

Do I need to reboot after patching?

For OS or kernel updates, yes. For most userland packages a systemctl restart <service> is enough. Any process that loaded the old shared library keeps using it until restarted, so when in doubt, reboot.

What is the CVSS score?

7.2 (high). Refer to the vendor advisory for the exact vector string.

Where is the official advisory?

See the References section at the bottom of this page; the vendor's URL is the authoritative source for affected builds and patched versions.

References

• Official vendor advisory: https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20190123-rv-inject
• NVD: https://nvd.nist.gov/vuln/detail/CVE-2019-1652
• CISA KEV catalog entry: https://www.cisa.gov/known-exploited-vulnerabilities-catalog
• https://www.exploit-db.com/exploits/46243/
• http://www.securityfocus.com/bid/106728
• http://seclists.org/fulldisclosure/2019/Mar/61
• https://seclists.org/bugtraq/2019/Mar/55

Written by Sai Kiran Pandrala on 2026-05-25. Always confirm against the vendor's advisory before applying changes in production.

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