CVE-2021-27708Public exploitNetwork attack vector

Unauthenticated command execution via unsanitized system call

Published Apr 14, 2021 · Updated Aug 3, 2024

OS command injection in TOTOLINK X5000R and A720R router firmware allows remote attackers to execute arbitrary commands via HTTP requests. In X5000R 9.1.0u.6118_B20201102 and A720R 4.1.5cu.470_B20200911, setTracerouteCfg passes the attacker-controlled command parameter to glibc's system function without neutralizing shell metacharacters. No credentials or user interaction are required, and successful exploitation runs commands on the router OS.

CVSS severity9.8
Critical
EPSS probability7.61%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

OS command injection in TOTOLINK X5000R and A720R router firmware allows remote attackers to execute arbitrary commands via HTTP requests. In X5000R 9.1.0u.6118_B20201102 and A720R 4.1.5cu.470_B20200911, setTracerouteCfg passes the attacker-controlled command parameter to glibc's system function without neutralizing shell metacharacters. No credentials or user interaction are required, and successful exploitation runs commands on the router OS.

The record

CVE
CVE-2021-27708
Published
Apr 14, 2021
Updated
Aug 3, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-78, T1059.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Apr 14, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 3, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

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
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-78Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection')
T1059.004Command and Scripting Interpreter: Unix Shell

Public exploit references

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

Technologies

Your stack

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo