CVE-2021-1159Network attack vector

Administrator-authenticated root execution or reload via stack overflow

Published Jan 13, 2021 · Updated Nov 12, 2024

Stack-based buffer overflows in Cisco Small Business RV router firmware allow remote authenticated users to execute root code or reload devices. The web management interface fails to validate user-supplied fields in crafted HTTP requests, allowing writes past stack buffers. Valid administrator credentials and access through the LAN interface or an enabled WAN management interface are required; exploitation grants root execution or reloads the device.

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 overflows in Cisco Small Business RV router firmware allow remote authenticated users to execute root code or reload devices. The web management interface fails to validate user-supplied fields in crafted HTTP requests, allowing writes past stack buffers. Valid administrator credentials and access through the LAN interface or an enabled WAN management interface are required; exploitation grants root execution or reloads the device.

The record

CVE
CVE-2021-1159
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
admin

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 privilegesadmin

What is affected?

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

Published CVSS scores

9.0NIST NVDAV:N/AC:L/Au:S/C:C/I:C/A:C
7.2Cisco Systems, Inc.CVSS: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
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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