CVE-2021-1330 – This vulnerability allows authenticated remote ... (How to Fix)

Q: What is the severity of CVE-2021-1330?

CVE-2021-1330 has a CVSS score of 7.2 (HIGH). This vulnerability allows authenticated remote attackers to execute arbitrary code as root or cause denial of service on affected Cisco Small Business routers. Attackers with administrator credentials can exploit improper input validation in the web management interface via crafted HTTP requests. Organizations using Cisco RV016, RV042, RV042G, RV082, RV320, or RV325 routers are affected.

📋 TL;DR

This vulnerability allows authenticated remote attackers to execute arbitrary code as root or cause denial of service on affected Cisco Small Business routers. Attackers with administrator credentials can exploit improper input validation in the web management interface via crafted HTTP requests. Organizations using Cisco RV016, RV042, RV042G, RV082, RV320, or RV325 routers are affected.

💻 Affected Systems

Products:

Cisco Small Business RV016
Cisco Small Business RV042
Cisco Small Business RV042G
Cisco Small Business RV082
Cisco Small Business RV320
Cisco Small Business RV325

Versions: All versions prior to patched firmware

Operating Systems: Embedded router OS

Default Config Vulnerable: ⚠️ Yes

Notes: Web management interface must be enabled (default). Requires valid administrator credentials for exploitation.

📦 What is this software?

⚠️ Risk & Real-World Impact

🔴

Worst Case

Complete device compromise with root-level arbitrary code execution, allowing attacker persistence, data theft, and network pivoting.

🟠

Likely Case

Denial of service through device reboots disrupting network connectivity for small businesses.

🟢

If Mitigated

Limited to authenticated attacks only, reducing exposure if strong credential policies are enforced.

🌐 Internet-Facing: HIGH

🏢 Internal Only: MEDIUM

🎯 Exploit Status

Public PoC: ✅ No

Weaponized: UNKNOWN

Unauthenticated Exploit: ✅ No

Complexity: MEDIUM

Requires authentication, but credential theft or weak passwords could facilitate exploitation.

🛠️ Fix & Mitigation

✅ Official Fix

Patch Version: Check Cisco advisory for specific firmware versions per model

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

Restart Required: Yes

Instructions:

1. Identify router model. 2. Visit Cisco Security Advisory. 3. Download appropriate firmware update. 4. Backup configuration. 5. Upload firmware via web interface. 6. Reboot device.

🔧 Temporary Workarounds

Disable Web Management Interface

all

Disable the vulnerable web interface and use alternative management methods

Restrict Management Access

all

Limit web interface access to specific trusted IP addresses only

🧯 If You Can't Patch

Implement strict network segmentation to isolate affected routers from critical systems
Enforce strong password policies and multi-factor authentication for admin accounts

🔍 How to Verify

Check if Vulnerable:

Check router firmware version against patched versions in Cisco advisory

Check Version:

Login to web interface > Administration > Firmware Upgrade to view current version

Verify Fix Applied:

Verify firmware version matches or exceeds patched version listed in advisory

📡 Detection & Monitoring

Log Indicators:

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

Network Indicators:

Unusual outbound connections from router
HTTP traffic patterns to management interface from unexpected sources

SIEM Query:

source="router_logs" AND (event="authentication_success" OR event="reboot") | stats count by src_ip

📊 Metadata

CVE ID: CVE-2021-1330

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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🔗 Related Vulnerabilities

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