CVE-2026-20408
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 · uneditedIn wlan, there is a possible out of bounds write due to a heap buffer overflow. This could lead to remote (proximal/adjacent) escalation of privilege with no additional execution privileges needed. User interaction is not needed for exploitation. Patch ID: WCNCR00461651; Issue ID: MSV-4758.
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 confidenceA heap buffer overflow vulnerability exists in the wlan (wireless LAN) driver component that allows an attacker in proximal/adjacent wireless range to perform an out-of-bounds write, leading to remote privilege escalation without requiring user interaction or additional execution privileges.
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<= 7.6.7.2= 19.07.0= 21.02.0= 23.05.0CVSS 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
- Adjacent
- Complexity
- Low
- Privileges
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- High
- Availability
- High
CVSS:3.1/AV:A/AC:L/PR:N/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 checksWork through these to decide whether this CVE applies to you.
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Identify Mediatek WLAN hardware in useCheck system documentation, device specs, or run 'lspci'/'lsusb' for Mediatek wireless adapters. Alternatively, check router firmware/build info for Mediatek chipset identifiers.Affected if Device uses Mediatek WLAN hardware and firmware version is unknown or <= 7.6.7.2
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Check Mediatek SDK versionIf running custom firmware built on Mediatek SDK, examine the SDK version file (typically in /usr/lib/mtk-sdk-ver or similar) or the firmware build metadata.Affected if Mediatek SDK version is <= 7.6.7.2
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Check OpenWrt versionRun 'cat /etc/openwrt_version' or 'cat /etc/os-release' on the device to determine the installed OpenWrt release.Affected if OpenWrt version is 19.07.0, 21.02.0, or 23.05.0
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Verify WLAN interface is enabledRun 'iwconfig' or 'ip link show' to confirm a wireless interface exists and is active (UP state).Affected if WLAN interface is present and enabled (the vulnerability requires the WLAN component to be running)
A system is affected if it uses Mediatek WLAN hardware/firmware with SDK <= 7.6.7.2, or runs OpenWrt 19.07.0/21.02.0/23.05.0, and has an active WLAN interface.
Generated from the published advisory. Verify against your own configuration.
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 dataApply the vendor patch (WCNCR00461651) to update the affected wireless firmware/driver. Given the proximal/adjacent attack vector, restrict wireless exposure and monitor for unauthorized devices in the area until the patch is deployed.
- Consultation3.0 h
- Implementation6.0 h
- Testing3.0 h
- Review / QA2.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2026-20408 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2026-20408 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- Version or environment caveats, and links to real fixes
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