CVE-2025-9791Public exploitNetwork attack vector

Authenticated code execution via unchecked wanMTU copy

Published Sep 1, 2025 · Updated Sep 2, 2025

Stack-based buffer overflow in Tenda AC20 16.03.08.05 allows remote authenticated users to execute code through a crafted WAN MTU request. The web service passes the wanMTU form value to strcpy, which writes into the fixed-size nptr stack buffer without checking the input length. A valid management cookie is required by the public proof of concept; overflow data can crash the router or redirect execution for arbitrary code.

CVSS severity8.8
High
EPSS probability0.84%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Stack-based buffer overflow in Tenda AC20 16.03.08.05 allows remote authenticated users to execute code through a crafted WAN MTU request. The web service passes the wanMTU form value to strcpy, which writes into the fixed-size nptr stack buffer without checking the input length. A valid management cookie is required by the public proof of concept; overflow data can crash the router or redirect execution for arbitrary code.

The record

CVE
CVE-2025-9791
Published
Sep 1, 2025
Updated
Sep 2, 2025
Vendor
Shenzhen Tenda Technology Co., Ltd.
Product
AC20
Classifications
CWE-119, CWE-787, CWE-121, T1190
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Sep 1, 2025CVE publishedPublication date reported by the CVE source.
  2. Sep 2, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=16.03.08.05

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Shenzhen Tenda Technology Co., Ltd. · AC20version=16.03.08.05

Published CVSS scores

8.8VulDBCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
7.4VulDBCVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:P
9.8NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
9.0VulDBAV:N/AC:L/Au:S/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 exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-119Improper Restriction of Operations within the Bounds of a Memory Buffer
CWE-787Out-of-bounds Write
CWE-121Stack-based Buffer Overflow
T1190Exploit Public-Facing Application

Public exploit references

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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