CVE-2026-36611
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 · uneditedMercusys AC12G (EU) V1 with firmware AC12G(EU)_V1_200909 returns 128 bytes of uninitialized buffer when receiving POST requests without SOAPAction header on UPnP port 1900, exposing internal memory to unauthenticated adjacent network attackers.
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 · high confidenceThe Mercusys AC12G router's UPnP service on port 1900 returns 128 bytes of uninitialized buffer memory when processing POST requests that lack a SOAPAction header. This information disclosure flaw allows unauthenticated adjacent network attackers to potentially read sensitive data from device memory.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
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
- Network
- Complexity
- Low
- Privileges
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- Low
- Integrity
- Low
- Availability
- Low
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L
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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Confirm device model is Mercusys AC12GAccess the router admin panel (typically at 192.168.0.1 or 192.168.1.1) and check the Device Info or Status page for the model name, or physically inspect the router labelAffected if The device model is Mercusys AC12G and the firmware is from an affected version range
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Verify UPnP service is enabledLog into the router admin panel, navigate to Advanced or Network settings, locate the UPnP setting, and confirm it is turned ONAffected if UPnP is enabled on the device (this is required for the vulnerability to be exploitable)
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Check if UPnP port 1900 is exposed on the networkFrom a computer on the same network, run a port scan targeting the router IP on UDP port 1900 (e.g., nmap -sU -p 1900 <router_ip>)Affected if Port 1900/UDP is open and responding on the router's IP address
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Verify firmware versionIn the router admin panel, go to Settings or System Tools > Firmware Upgrade or Device Info, and record the firmware version numberAffected if The installed firmware version matches or falls within any known affected version ranges for this CVE
The device is affected if it is a Mercusys AC12G router with UPnP enabled and port 1900/UDP is accessible from the network.
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 dataRestrict access to UPnP port 1900 via firewall rules or network segmentation to prevent unauthorized adjacent attackers. If available, apply vendor firmware updates; otherwise, consider replacing the affected device.
- Consultation4.0 h
- Implementation6.0 h
- Testing4.0 h
- Review / QA2.0 h
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Free · runs locallyCheck whether your project pulls in CVE-2026-36611 — 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-2026-36611 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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- Verified mitigations, workarounds, and config changes
- Version or environment caveats, and links to real fixes
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