CVE-2025-8939Public exploitNetwork attack vector

Authenticated code execution via unchecked shareSpeed copy

Published Aug 14, 2025 · Updated Aug 15, 2025

Buffer overflow in AC20 firmware 16.03.08.0 through 16.03.08.12 allows remote authenticated users to execute code via a crafted shareSpeed value. The fromSetWifiGusetBasic function copies the HTTP parameter into the src_1 array without checking its length. Access to the router management endpoint is required; an oversized value demonstrably crashes the service, while the report also identifies command execution.

CVSS severity8.8
High
EPSS probability0.90%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Buffer overflow in AC20 firmware 16.03.08.0 through 16.03.08.12 allows remote authenticated users to execute code via a crafted shareSpeed value. The fromSetWifiGusetBasic function copies the HTTP parameter into the src_1 array without checking its length. Access to the router management endpoint is required; an oversized value demonstrably crashes the service, while the report also identifies command execution.

The record

CVE
CVE-2025-8939
Published
Aug 14, 2025
Updated
Aug 15, 2025
Vendor
Shenzhen Tenda Technology Co., Ltd.
Product
AC20
Classifications
CWE-120, CWE-119
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Aug 14, 2025CVE publishedPublication date reported by the CVE source.
  2. Aug 15, 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=16.03.08.0
  2. Affected versionversion=16.03.08.1
  3. Affected versionversion=16.03.08.10
  4. Affected versionversion=16.03.08.11
  5. Affected versionversion=16.03.08.12
  6. Affected versionversion=16.03.08.2
  7. Affected versionversion=16.03.08.3
  8. Affected versionversion=16.03.08.4
  9. Affected versionversion=16.03.08.5
  10. Affected versionversion=16.03.08.6
  11. Affected versionversion=16.03.08.7
  12. Affected versionversion=16.03.08.8
  13. Affected versionversion=16.03.08.9

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Shenzhen Tenda Technology Co., Ltd. · AC20version=16.03.08.0; version=16.03.08.1; version=16.03.08.10; version=16.03.08.11; version=16.03.08.12; version=16.03.08.2; version=16.03.08.3; version=16.03.08.4; version=16.03.08.5; version=16.03.08.6; version=16.03.08.7; version=16.03.08.8; version=16.03.08.9

Published CVSS scores

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
9.0VulDBAV:N/AC:L/Au:S/C:C/I:C/A:C
8.8VulDBCVSS:3.1/AV:N/AC:L/PR:L/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.

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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
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-120Buffer Copy without Checking Size of Input ('Classic Buffer Overflow')
CWE-119Improper Restriction of Operations within the Bounds of a Memory Buffer

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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