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CVE Record

CVE-2021-35393: Realtek Jungle SDK version v2.x up to v3.4.14B provides a 'WiFi Simple Config' server that implements both...

Realtek Jungle SDK version v2.x up to v3.4.14B provides a 'WiFi Simple Config' server that implements both UPnP and SSDP protocols. The binary is usually named wscd or mini_upnpd and is the successor to miniigd. The server is vulnerable to a stack buffer overflow vulnerability that is present due to unsafe parsing of the UPnP SUBSCRIBE/UNSUBSCRIBE Callback header. Successful exploitation of this vulnerability allows remote unauthenticated attackers to gain arbitrary code execution on the affected device.

UnknownCVSS not scoredNot KEV-listedUpdated
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Glexia's TakeAutomated analysiscritical

Security readout for executives and security teams

Plain-English summary

This flaw affects Realtek Jungle SDK code embedded in some networking or IoT devices. An unauthenticated remote attacker could exploit unsafe UPnP callback parsing to execute code on an affected device. The provided sources do not list specific OEM devices or firmware fixes, so exposure depends on vendor firmware contents.

Executive priority

Treat this as high-priority asset exposure work because the impact is remote unauthenticated code execution on embedded devices. Urgency is highest where affected services are reachable outside tightly controlled networks.

Technical view

CVE-2021-35393 is a stack buffer overflow in the Realtek Jungle SDK WiFi Simple Config server, typically named wscd or mini_upnpd. Affected SDK versions are v2.x through v3.4.14B. The issue is triggered through unsafe parsing of UPnP SUBSCRIBE or UNSUBSCRIBE Callback headers and may allow unauthenticated remote code execution.

Likely exposure

Organizations may be exposed through routers, gateways, access points, or IoT devices built with the affected Realtek SDK. The provided bundle does not identify specific downstream products, CPEs, or vendors.

Exploitation context

The source bundle supports unauthenticated remote code execution impact, but does not show CISA KEV listing or evidence of active exploitation. Do not assume exploitation is occurring without separate threat intelligence.

Researcher notes

The strongest evidence is the CVE description and Realtek/IOT Inspector references. The bundle lacks CVSS, CWE, product CPEs, exploit status, and explicit fix details, so validation should focus on firmware provenance and vendor confirmation.

Mitigation direction

  • Check Realtek advisory and device-vendor firmware guidance for CVE-2021-35393.
  • Ask OEMs whether deployed firmware uses Realtek Jungle SDK v2.x through v3.4.14B.
  • Prioritize firmware updates for exposed networking and IoT infrastructure.
  • Limit UPnP, SSDP, and WiFi Simple Config exposure to trusted networks where possible.
  • Retire devices whose vendors cannot confirm fixed firmware.

Validation and detection

  • Inventory devices using Realtek-based router, gateway, access point, or IoT firmware.
  • Check firmware SBOMs or vendor notices for Realtek Jungle SDK version references.
  • Look for wscd, mini_upnpd, or WiFi Simple Config components in firmware evidence.
  • Confirm whether UPnP or SSDP services are enabled and reachable.
  • Document vendor responses and firmware remediation status per device model.
Prepared
Confidence
medium
Sources
5

Public sources used

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

Conservative CVE-to-ATT&CK context

These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.

ATT&CK lookup starting points

Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.

description · low confidence lookup

Execution behavior lookup

The CVE wording references code or command execution, so execution technique review may help defensive triage. This is a Glexia inferred lookup path, not an official MITRE, ATT&CK, or CVE Program mapping.

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cve · low confidence lookup

CVE-2021-35393 mapping review

Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.

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Vulnerability profileCVE Program record
Severity
Unknown
CVSS
Not scored
Known Exploited
No
Published
Official CVE source material

CNA and ADP enrichment extracted from CVE v5

These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.

0CVSS vectors
0Timeline events
0ADP providers
4Source links

CVSS and timeline data

No CVSS vectors or timeline events were available in the normalized CVE source material.

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
n/an/an/aListed
Weakness

CWE details

No CWE listed

CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.