CVE-2025-31355Network attack vector

Persistent code execution via unsigned firmware updates

Published Aug 20, 2025 · Updated Nov 3, 2025

Firmware integrity failure in Tenda AC6 V5.0 V02.03.01.110 allows remote authenticated users to execute code via a malicious update. The check_upgrade_file path accepts an image when its magic value, size, and attacker-computable CRC match, without verifying a cryptographic signature. Administrative web-portal credentials are required, after which arbitrary firmware can be flashed for persistent control of the router.

CVSS severity7.2
High
EPSS probability0.30%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Firmware integrity failure in Tenda AC6 V5.0 V02.03.01.110 allows remote authenticated users to execute code via a malicious update. The check_upgrade_file path accepts an image when its magic value, size, and attacker-computable CRC match, without verifying a cryptographic signature. Administrative web-portal credentials are required, after which arbitrary firmware can be flashed for persistent control of the router.

The record

CVE
CVE-2025-31355
Published
Aug 20, 2025
Updated
Nov 3, 2025
Vendor
Shenzhen Tenda Technology Co., Ltd.
Product
AC6
Classifications
CWE-494, T1601.001
Attack vector
network
Privileges
admin

Timeline

How it unfolded

  1. Aug 20, 2025CVE publishedPublication date reported by the CVE source.
  2. Nov 3, 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=V02.03.01.110

What conditions does exploitation require?

Attack vectornetwork
Required privilegesadmin

What is affected?

Shenzhen Tenda Technology Co., Ltd. · AC6version=V02.03.01.110

Published CVSS scores

7.2Cisco TalosCVSS:3.1/AV:N/AC:L/PR:H/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 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesadmin
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-494Download of Code Without Integrity Check
T1601.001System Firmware

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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