CVE-2021-34730Network attack vector

Root code execution or reload via UPnP requests

Published Aug 18, 2021 · Updated Nov 7, 2024

Stack-based buffer overflow in Cisco Small Business RV110W, RV130, RV130W, and RV215W routers allows remote attackers to execute root code. The UPnP service improperly validates crafted request data and writes beyond a stack buffer, corrupting control data used by the request handler. Exploitation requires UPnP to be enabled; successful requests execute code as root or reload the appliance, while WAN exposure is disabled by default.

CVSS severity9.8
Critical
EPSS probability18.50%
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 RV110W, RV130, RV130W, and RV215W routers allows remote attackers to execute root code. The UPnP service improperly validates crafted request data and writes beyond a stack buffer, corrupting control data used by the request handler. Exploitation requires UPnP to be enabled; successful requests execute code as root or reload the appliance, while WAN exposure is disabled by default.

The record

CVE
CVE-2021-34730
Published
Aug 18, 2021
Updated
Nov 7, 2024
Vendor
ClamAV
Product
Cisco Small Business RV Series Router Firmware
Classifications
CWE-121, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 18, 2021CVE publishedPublication date reported by the CVE source.
  2. Nov 7, 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?

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  1. Affected versionversion=n/a

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

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

Published CVSS scores

9.8CiscoCVSS:3.1/AV:N/AC:L/PR:N/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 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
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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