CVE-2023-39785Network attack vector

Router crash via unbounded QoS list copy

Published Aug 21, 2023 · Updated Jul 9, 2026

A stack overflow in Tenda AC8 v4.0 firmware 16.03.34.06 allows remote attackers to crash the router through a crafted QoS list. The SetNetControlList handler passes the list form value through set_qosMib_list to strcpy without bounding the destination buffer. No authentication or user interaction is required; successful exploitation interrupts routing service without reported data disclosure or modification.

CVSS severity7.5
High
EPSS probability0.81%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

A stack overflow in Tenda AC8 v4.0 firmware 16.03.34.06 allows remote attackers to crash the router through a crafted QoS list. The SetNetControlList handler passes the list form value through set_qosMib_list to strcpy without bounding the destination buffer. No authentication or user interaction is required; successful exploitation interrupts routing service without reported data disclosure or modification.

The record

CVE
CVE-2023-39785
Published
Aug 21, 2023
Updated
Jul 9, 2026
Vendor
Shenzhen Tenda Technology Co., Ltd.
Product
Tenda AC8 Firmware
Classifications
CWE-787, T1499
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 21, 2023CVE publishedPublication date reported by the CVE source.
  2. Jul 9, 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?

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

  1. Affected versionversion=16.03.34.06

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Shenzhen Tenda Technology Co., Ltd. · Tenda AC8 Firmwareversion=16.03.34.06

Published CVSS scores

7.5NIST National Vulnerability DatabaseCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/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.

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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-787Out-of-bounds Write
T1499Endpoint Denial of Service

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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