CVE-2021-1332 – This vulnerability allows authenticated attacke... (How to Fix)

Q: What is the severity of CVE-2021-1332?

CVE-2021-1332 has a CVSS score of 7.2 (HIGH). This vulnerability allows authenticated attackers with administrator credentials to execute arbitrary code as root or cause denial of service on affected Cisco Small Business routers. The issue stems from improper input validation in the web management interface. Organizations using these specific router models are at risk.

📋 TL;DR

This vulnerability allows authenticated attackers with administrator credentials to execute arbitrary code as root or cause denial of service on affected Cisco Small Business routers. The issue stems from improper input validation in the web management interface. Organizations using these specific router models are at risk.

💻 Affected Systems

Products:

Cisco Small Business RV016
RV042
RV042G
RV082
RV320
RV325 Routers

Versions: All versions prior to the fixed releases

Operating Systems: Embedded router OS

Default Config Vulnerable: ⚠️ Yes

Notes: Requires valid administrator credentials to exploit

📦 What is this software?

⚠️ Risk & Real-World Impact

🔴

Worst Case

Complete device compromise with root-level arbitrary code execution, allowing full control of the router and potential lateral movement into connected networks.

🟠

Likely Case

Denial of service through device reboots, disrupting network connectivity for connected users and services.

🟢

If Mitigated

Limited impact if strong authentication controls prevent unauthorized access to admin credentials.

🌐 Internet-Facing: HIGH

🏢 Internal Only: MEDIUM

🎯 Exploit Status

Public PoC: ✅ No

Weaponized: UNKNOWN

Unauthenticated Exploit: ✅ No

Complexity: LOW

Exploitation requires authenticated access but is straightforward once credentials are obtained

🛠️ Fix & Mitigation

✅ Official Fix

Patch Version: RV016: 4.2.3.14, RV042/RV042G: 4.2.3.14, RV082: 4.2.3.14, RV320/RV325: 1.5.1.11

Vendor Advisory: https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-rv-overflow-ghZP68yj

Restart Required: Yes

Instructions:

1. Log into router web interface. 2. Navigate to Administration > Firmware Upgrade. 3. Download appropriate firmware from Cisco website. 4. Upload and install firmware. 5. Reboot router after installation.

🔧 Temporary Workarounds

Restrict Web Management Access

all

Limit web management interface access to trusted IP addresses only

Use Strong Authentication

all

Implement complex administrator passwords and consider multi-factor authentication if supported

🧯 If You Can't Patch

Disable web management interface if not needed and use CLI/SSH instead
Implement network segmentation to isolate routers from untrusted networks

🔍 How to Verify

Check if Vulnerable:

Check router firmware version via web interface: Status > Router > Firmware Version

Check Version:

No CLI command available - use web interface at Status > Router > Firmware Version

Verify Fix Applied:

Verify firmware version matches or exceeds patched versions listed in vendor advisory

📡 Detection & Monitoring

Log Indicators:

Multiple failed login attempts followed by successful admin login
Unusual HTTP POST requests to management interface
Device reboot logs without scheduled maintenance

Network Indicators:

Unusual outbound connections from router after admin login
HTTP traffic patterns matching exploit payloads

SIEM Query:

source="router_logs" (event="authentication_success" user="admin") OR (event="device_reboot" reason="unexpected")

📊 Metadata

CVE ID: CVE-2021-1332

CVSS v3 Score: 7.2 (HIGH)

CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H

CWE: CWE-121

Published: February 4, 2021

Last Updated: November 21, 2024

🔗 References

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