CVE-2021-41653Known exploitationPublic exploitNetwork attack vector

Authenticated command execution via unsanitized PING host

Published Nov 13, 2021 · Updated Jul 9, 2026

Command injection in TP-Link TL-WR840N EU v5 firmware through TL-WR840N(EU)_V5_171211 allows remote authenticated users to execute commands. The PING function passes the user-controlled host parameter to a system ping command without server-side sanitization, while its client-side validation can be bypassed. Administrative web access and an active WAN connection are required; successful exploitation yields a root shell and full control of the router.

CVSS severity9.8
Critical
EPSS probability76.05%
Next 30 days · Sep 16, 2026
Known exploitationReported
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Command injection in TP-Link TL-WR840N EU v5 firmware through TL-WR840N(EU)_V5_171211 allows remote authenticated users to execute commands. The PING function passes the user-controlled host parameter to a system ping command without server-side sanitization, while its client-side validation can be bypassed. Administrative web access and an active WAN connection are required; successful exploitation yields a root shell and full control of the router.

The record

CVE
CVE-2021-41653
Published
Nov 13, 2021
Updated
Jul 9, 2026
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-94, T1059.004, T1190
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Nov 13, 2021CVE publishedPublication date reported by the CVE source.
  2. Nov 22, 2021Exploitation reportedMANGA botnet exploitation
  3. Jul 9, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

9.8NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
10.0NIST NVDAV:N/AC:L/Au:N/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
Privilegesauthenticated
Known exploitationReported
Public exploitPublished

Weakness, pattern, technique

CWE-94Improper Control of Generation of Code ('Code Injection')
T1059.004Unix Shell
T1190Exploit Public-Facing Application

Public exploit references

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

Reported exploitation

Technologies

Your stack

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Your stack

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