CVE-2021-1209Network attack vector

Authenticated remote code execution via input validation flaw

Published Jan 13, 2021 · Updated Nov 12, 2024

A command execution vulnerability in Cisco Small Business RV routers allows remote authenticated attackers to execute arbitrary code via crafted HTTP requests. The web-based management interface improperly validates user-supplied input before processing HTTP requests, enabling command injection that runs with root privileges. Exploitation requires valid administrator credentials and access to the management interface; a successful attack can execute code as root or reload the device, causing denial of service.

CVSS severity7.2
High
EPSS probability2.19%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

A command execution vulnerability in Cisco Small Business RV routers allows remote authenticated attackers to execute arbitrary code via crafted HTTP requests. The web-based management interface improperly validates user-supplied input before processing HTTP requests, enabling command injection that runs with root privileges. Exploitation requires valid administrator credentials and access to the management interface; a successful attack can execute code as root or reload the device, causing denial of service.

The record

CVE
CVE-2021-1209
Published
Jan 13, 2021
Updated
Nov 12, 2024
Vendor
ClamAV
Product
Cisco Small Business RV Series Router Firmware
Classifications
CWE-121, T1190
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Jan 13, 2021CVE publishedPublication date reported by the CVE source.
  2. Nov 12, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=n/a

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

ClamAV · Cisco Small Business RV Series Router Firmwareversion=n/a

Published CVSS scores

7.2Cisco PSIRTCVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-121Improper Validation of Array Index
T1190Exploit Public-Facing Application

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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