CVE-2021-1347Network attack vector

Authenticated RCE or DoS via stack overflow

Published Feb 4, 2021 · Updated Nov 8, 2024

Stack-based buffer overflow in Cisco RV Series router firmware allows remote authenticated users to execute code or reload devices via crafted HTTP requests. The web-based management interface fails to validate user-supplied input, allowing crafted requests to overwrite stack memory. Valid administrator credentials are required, and remote management is disabled by default; successful exploitation runs as root or reloads the appliance, interrupting service.

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 RV Series router firmware allows remote authenticated users to execute code or reload devices via crafted HTTP requests. The web-based management interface fails to validate user-supplied input, allowing crafted requests to overwrite stack memory. Valid administrator credentials are required, and remote management is disabled by default; successful exploitation runs as root or reloads the appliance, interrupting service.

The record

CVE
CVE-2021-1347
Published
Feb 4, 2021
Updated
Nov 8, 2024
Vendor
ClamAV
Product
Cisco Small Business RV Series Router Firmware
Classifications
CWE-121, T1203
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

7.2Cisco Systems, Inc.CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H
9.0NVDAV:N/AC:L/Au:S/C:C/I:C/A:C

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
Privilegesadmin
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-121Stack-based Buffer Overflow
T1203Exploitation for Client Execution

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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