CVE-2026-31255Network attack vector

Authenticated command execution via guestuser injection

Published Apr 27, 2026 · Updated Apr 27, 2026

Command injection in Tenda AC18 firmware 15.03.05.05_multi allows remote authenticated users to execute system commands via a crafted guestuser value. The /goform/SetSambaCfg handler fails to neutralize command syntax in the guestuser parameter before using it for system command execution. Low-privileged access to the management interface is sufficient, and successful injection executes commands in the router firmware context.

CVSS severity9.8
Critical
EPSS probability1.12%
Next 30 days · Sep 17, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Command injection in Tenda AC18 firmware 15.03.05.05_multi allows remote authenticated users to execute system commands via a crafted guestuser value. The /goform/SetSambaCfg handler fails to neutralize command syntax in the guestuser parameter before using it for system command execution. Low-privileged access to the management interface is sufficient, and successful injection executes commands in the router firmware context.

The record

CVE
CVE-2026-31255
Published
Apr 27, 2026
Updated
Apr 27, 2026
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-77, T1059
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Apr 27, 2026CVE publishedPublication date reported by the CVE source.
  2. Apr 27, 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

5.4CISA-ADPCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N
9.8NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/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
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-77Improper Neutralization of Special Elements used in a Command ('Command Injection')
T1059Command and Scripting Interpreter

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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