CVE-2021-1334Network attack vector

Root code execution or reload via buffer overflow

Published Feb 4, 2021 · Updated Nov 8, 2024

Stack-based buffer overflow in Cisco Small Business RV router web management allows remote authenticated users to execute root code or reload devices. The interface improperly validates attacker-controlled data in crafted HTTP requests, allowing a stack buffer to overflow; Cisco has not disclosed a specific handler or parameter. Valid administrator credentials and LAN access are required unless remote management is enabled, while successful exploitation runs code as root or forces a device reload.

CVSS severity7.2
High
EPSS probability2.75%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Stack-based buffer overflow in Cisco Small Business RV router web management allows remote authenticated users to execute root code or reload devices. The interface improperly validates attacker-controlled data in crafted HTTP requests, allowing a stack buffer to overflow; Cisco has not disclosed a specific handler or parameter. Valid administrator credentials and LAN access are required unless remote management is enabled, while successful exploitation runs code as root or forces a device reload.

The record

CVE
CVE-2021-1334
Published
Feb 4, 2021
Updated
Nov 8, 2024
Vendor
ClamAV
Product
Cisco Small Business RV Series Router Firmware
Classifications
CWE-121, T1190
Attack vector
network
Privileges
admin

Timeline

How it unfolded

  1. Feb 4, 2021CVE publishedPublication date reported by the CVE source.
  2. Nov 8, 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 privilegesadmin

What is affected?

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

Published CVSS scores

7.2CiscoCVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H/E:X/RL:X/RC:X

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 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesadmin
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-121Stack-based Buffer Overflow
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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