EUVD-2026-25898Severity by source
AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Primary rating from NVD · only source for this CVE.
CVSS VectorNVD
Lifecycle Timeline
6DescriptionCVE.org
A command injection vulnerability exists in Tenda AC18 V15.03.05.05_multi. The vulnerability is located in the /goform/SetSambaCfg interface, where improper handling of the guestuser parameter allows attackers to execute arbitrary system commands.
AnalysisAI
Remote unauthenticated command injection in Tenda AC18 router firmware V15.03.05.05_multi allows complete device compromise via the SetSambaCfg interface. Attackers can execute arbitrary system commands by manipulating the guestuser parameter in HTTP requests to /goform/SetSambaCfg. CVSS 9.8 critical severity with network attack vector and no authentication required. EPSS score of 0.06% (19th percentile) suggests low observed exploitation despite extreme technical severity. Publicly documented exploit proof-of-concept exists on GitHub.
Technical ContextAI
The vulnerability affects the Samba/SMB file sharing configuration interface in Tenda AC18 wireless router firmware. The /goform/SetSambaCfg endpoint processes configuration parameters for network file sharing but fails to sanitize the guestuser parameter before passing it to system command execution functions. This is a classic CWE-77 command injection flaw where user-controlled input is concatenated into shell commands without proper escaping or validation. The affected firmware version V15.03.05.05_multi runs on embedded Linux systems typical of consumer routers, where web interfaces execute commands with root privileges. Router management interfaces commonly process configuration parameters through CGI-like handlers that directly invoke system utilities, making command injection particularly dangerous since successful exploitation grants complete administrative control over the device.
RemediationAI
No vendor-released patch identified at time of analysis-Tenda has not published security advisories or firmware updates addressing CVE-2026-31255 according to available references. Until vendor patches become available, implement these compensating controls: (1) Disable remote management access to the router's web interface-restrict admin panel access to LAN-only connections by disabling WAN-side management in router settings under System Administration or Remote Management; this prevents internet-based exploitation but does not protect against LAN-based attackers. (2) Disable Samba/SMB file sharing functionality entirely if not required for network operations; this removes the vulnerable /goform/SetSambaCfg endpoint from the attack surface but eliminates file sharing capability. (3) Deploy network segmentation to isolate the router's management interface on a dedicated VLAN accessible only to authorized administrators; this reduces exposure but requires additional network infrastructure. (4) Monitor for replacement-consider migrating to alternative router hardware with active security support, as consumer router vendors including Tenda have poor track records for publishing timely security patches for end-of-life firmware. Reference: https://github.com/izxnfirh8148/CVE_REQUESTS_references/blob/main/Tenda_AC18/Tenda_AC18_3th/README.md contains technical details but no remediation guidance.
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Same weakness CWE-77 – Command Injection
View allSame technique Command Injection
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External POC / Exploit Code
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