CVE-2021-27691Network attack vector

Unauthenticated command execution via formSetDebugCfg system call

Published Apr 15, 2021 · Updated Aug 3, 2024

Command injection in Tenda G0, G1, and G3 firmware allows remote attackers to execute arbitrary OS commands via action/setDebugCfg. The formSetDebugCfg function passes untrusted request input to the glibc system function, causing a shell to interpret attacker-controlled data. No authentication or user interaction is required; the affected builds are G0 15.11.0.5(5876)_CN and 15.11.0.6(9039)_CN, and G1/G3 15.11.0.16(9024)_CN and 15.11.0.17(9502)_CN.

CVSS severity9.8
Critical
EPSS probability25.18%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Command injection in Tenda G0, G1, and G3 firmware allows remote attackers to execute arbitrary OS commands via action/setDebugCfg. The formSetDebugCfg function passes untrusted request input to the glibc system function, causing a shell to interpret attacker-controlled data. No authentication or user interaction is required; the affected builds are G0 15.11.0.5(5876)_CN and 15.11.0.6(9039)_CN, and G1/G3 15.11.0.16(9024)_CN and 15.11.0.17(9502)_CN.

The record

CVE
CVE-2021-27691
Published
Apr 15, 2021
Updated
Aug 3, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-119, CWE-78, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Apr 15, 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

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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 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 exploitUnconfirmed

Weakness, pattern, technique

CWE-119Improper Restriction of Operations within the Bounds of a Memory Buffer
CWE-78Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection')
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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