Vulnerability record

CVE-2021-35394

Realtek Jungle SDK Remote Code Execution Vulnerability

CriticalExploitation confirmedCISA KEV

What should I do?

This vulnerability is in the CISA Known Exploited Vulnerabilities catalog: attackers are using it. If you run Jungle Software Development Kit (SDK), fix it now.

CISA required action: Apply updates per vendor instructions.

US federal civilian agencies must remediate by Dec 24, 2021.

Patch status

Official fix available since Sep 30, 2026

Apply the vendor's update to every affected system. Check the fixed-in versions below where known.

Basis: NVD patch reference

Description

Realtek Jungle SDK version v2.x up to v3.4.14B provides a diagnostic tool called 'MP Daemon' that is usually compiled as 'UDPServer' binary. The binary is affected by multiple memory corruption vulnerabilities and an arbitrary command injection vulnerability that can be exploited by remote unauthenticated attackers.

Source: NIST National Vulnerability Database. Official vulnerability data, reproduced as published.

Affected products

Products affected by this vulnerability, with versions and the source of each entry
Product	Vendor	Source
Jungle Software Development Kit (SDK)	Realtek	KEV

Sources: KEV = CISA Known Exploited Vulnerabilities catalog. Version details have not been published yet.

Intelligence timeline

Developments from the last 30 days, newest first.

CVSS scoredUpdateKEVSep 30, 2026
CVE-2021-35394 scored CVSS 9.8: Realtek Jungle Software Development Kit (SDK), Realtek Jungle SDK Remote Code Execution Vulnerability
CISA lists this as exploited in the wild. Unpatched Jungle Software Development Kit (SDK) systems are exposed to active attacks now.
Basis: NIST National Vulnerability Database
Patch releasedUpdateKEVSep 30, 2026
Patch released for CVE-2021-35394: Realtek Jungle Software Development Kit (SDK), Realtek Jungle SDK Remote Code Execution Vulnerability
An official fix is now available for Realtek Jungle Software Development Kit (SDK). This vulnerability is being exploited, so apply it promptly.
Basis: NVD patch reference

1 earlier event is available with a subscription. See plans.

Coverage

We have not published a story about this vulnerability yet.

References

nvd.nist.gov https://nvd.nist.gov/vuln/detail/CVE-2021-35394
iot-inspector.com https://www.iot-inspector.com/blog/advisory-multiple-issues-realtek-sdk-iot-supply-chain
realtek.com https://www.realtek.com/en/cu-1-en/cu-1-taiwan-en
realtek.com https://www.realtek.com/images/safe-report/Realtek_APRouter_SDK_Advisory-CVE-2021-35392_35395.pdf
securityfocus.com https://www.securityfocus.com/archive/1/534765
cisa.gov https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-35394