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Software Development KitApplication · Mediatek

CVE-2025-20739

MEDIUM · 6.7 CVSS v3.1 Published 2025-11-04
Fix available
A fix is available. Upgrade to after 7.6.7.2 or later.
See remediation →
69/100
Remediation priority · Elevated
Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
In wlan AP driver, there is a possible out of bounds write due to an incorrect bounds check. This could lead to local escalation of privilege if a malicious actor has already obtained the System privilege. User interaction is not needed for exploitation. Patch ID: WCNCR00435340; Issue ID: MSV-4038.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · moderate confidence

A buffer overflow vulnerability exists in the WLAN AP driver where an incorrect bounds check allows an out-of-bounds write operation. An attacker who already has System-level privileges can exploit this to escalate to higher privileges. The vulnerability is in driver-level code and does not require user interaction.

MitigationApply the vendor patch (WCNCR00435340) to update the WLAN AP driver. Since this is a driver vulnerability, ensure the updated driver is deployed through standard firmware/software update mechanisms.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
Software Development KitApplication
Affected:<= 7.6.7.2
OpenwrtOperating system
Affected:= 19.07.0= 21.02.0

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Local
Complexity
Low
Privileges
High
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Identify the product in use
    Determine if the target system uses Mediatek Software Development Kit or Openwrt as its operating environment. This may be visible in system documentation, firmware metadata, or boot logs.
    Affected if The product is Mediatek SDK <= 7.6.7.2 or Openwrt version 19.07.0 or 21.02.0
  2. Check the installed SDK or Openwrt version
    Run 'cat /etc/version' or check the firmware/build manifest to obtain the exact version number of the Mediatek SDK or Openwrt installation. Compare this against the affected version ranges: Mediatek SDK <= 7.6.7.2, Openwrt 19.07.0, or Openwrt 21.02.0.
    Affected if The installed version falls within or below the affected ranges (SDK <= 7.6.7.2, or exactly 19.07.0 or 21.02.0 for Openwrt)
  3. Verify WLAN AP driver is loaded and active
    Check if the WLAN AP driver module is currently loaded or running. On Openwrt this can be done via 'lsmod' to list loaded kernel modules, or check for WLAN interface presence using 'iwconfig' or 'ip link show'. Look for wireless AP-related driver entries.
    Affected if The WLAN AP driver is loaded and operational, making the vulnerability surface accessible
  4. Check WLAN driver or firmware version
    Query the wireless driver version if exposed. Commands such as 'wlanconfig' (if available), checking /sys/class/net/*/device/ (for wireless interfaces), or reviewing the firmware version string from 'dmesg' grep for 'wlan' or 'wireless' may reveal version identifiers associated with the driver.
    Affected if The driver/firmware version cannot be determined or is below the patched version (WCNCR00435340)

The environment is affected if it runs Mediatek SDK <= 7.6.7.2 or Openwrt 19.07.0/21.02.0 with the WLAN AP driver enabled, where the driver lacks the WCNCR00435340 patch.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

From vendor data
Upgrade available Upgrade to a release after 7.6.7.2
Interim mitigation

Apply the vendor patch (WCNCR00435340) to update the WLAN AP driver. Since this is a driver vulnerability, ensure the updated driver is deployed through standard firmware/software update mechanisms.

Fix this in Software Development Kit Scoped from the published advisory
  • Consultation4.0 h
  • Implementation8.0 h
  • Testing12.0 h
  • Review / QA4.0 h
28.0 hours of engineering $4,760
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2025-20739 in production — separate from our analysis above.

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data